diff --git a/Src/Directory.Build.props b/Src/Directory.Build.props
index a570e7e9..3df27f22 100644
--- a/Src/Directory.Build.props
+++ b/Src/Directory.Build.props
@@ -6,7 +6,7 @@
     <MicrosoftCodeAnalysisFxCopAnalyzersPackageVersion>2.9.2</MicrosoftCodeAnalysisFxCopAnalyzersPackageVersion>
     <MicrosoftCSharpPackageVersion>4.3.0</MicrosoftCSharpPackageVersion>
     <MicrosoftSourceLinkGitHubPackageVersion>1.0.0-beta2-19367-01</MicrosoftSourceLinkGitHubPackageVersion>
-    <MicrosoftNetCompilersToolsetPackageVersion>3.3.0-beta1-final</MicrosoftNetCompilersToolsetPackageVersion>
+    <MicrosoftNetCompilersToolsetPackageVersion>3.3.1-beta3-final</MicrosoftNetCompilersToolsetPackageVersion>
     <MicrosoftNETTestSdkPackageVersion>15.7.2</MicrosoftNETTestSdkPackageVersion>
     <MoqPackageVersion>4.8.1</MoqPackageVersion>
     <NunitPackageVersion>3.11.0</NunitPackageVersion>
diff --git a/Src/Newtonsoft.Json/Converters/BinaryConverter.cs b/Src/Newtonsoft.Json/Converters/BinaryConverter.cs
index bd45657e..7390503a 100644
--- a/Src/Newtonsoft.Json/Converters/BinaryConverter.cs
+++ b/Src/Newtonsoft.Json/Converters/BinaryConverter.cs
@@ -71,7 +71,7 @@ namespace Newtonsoft.Json.Converters
             if (value.GetType().FullName == BinaryTypeName)
             {
                 EnsureReflectionObject(value.GetType());
-                Debug.Assert(_reflectionObject != null);
+                MiscellaneousUtils.Assert(_reflectionObject != null);
 
                 return (byte[])_reflectionObject.GetValue(value, BinaryToArrayName)!;
             }
@@ -142,7 +142,7 @@ namespace Newtonsoft.Json.Converters
             if (t.FullName == BinaryTypeName)
             {
                 EnsureReflectionObject(t);
-                Debug.Assert(_reflectionObject != null);
+                MiscellaneousUtils.Assert(_reflectionObject != null);
 
                 return _reflectionObject.Creator!(data);
             }
diff --git a/Src/Newtonsoft.Json/Converters/EntityKeyMemberConverter.cs b/Src/Newtonsoft.Json/Converters/EntityKeyMemberConverter.cs
index f7a90fb8..4670dba4 100644
--- a/Src/Newtonsoft.Json/Converters/EntityKeyMemberConverter.cs
+++ b/Src/Newtonsoft.Json/Converters/EntityKeyMemberConverter.cs
@@ -60,7 +60,7 @@ namespace Newtonsoft.Json.Converters
             }
 
             EnsureReflectionObject(value.GetType());
-            Debug.Assert(_reflectionObject != null);
+            MiscellaneousUtils.Assert(_reflectionObject != null);
 
             DefaultContractResolver? resolver = serializer.ContractResolver as DefaultContractResolver;
 
@@ -117,7 +117,7 @@ namespace Newtonsoft.Json.Converters
         public override object? ReadJson(JsonReader reader, Type objectType, object? existingValue, JsonSerializer serializer)
         {
             EnsureReflectionObject(objectType);
-            Debug.Assert(_reflectionObject != null);
+            MiscellaneousUtils.Assert(_reflectionObject != null);
 
             object entityKeyMember = _reflectionObject.Creator!();
 
diff --git a/Src/Newtonsoft.Json/Converters/IsoDateTimeConverter.cs b/Src/Newtonsoft.Json/Converters/IsoDateTimeConverter.cs
index 49977b5e..d9c8ee23 100644
--- a/Src/Newtonsoft.Json/Converters/IsoDateTimeConverter.cs
+++ b/Src/Newtonsoft.Json/Converters/IsoDateTimeConverter.cs
@@ -57,7 +57,7 @@ namespace Newtonsoft.Json.Converters
         public string? DateTimeFormat
         {
             get => _dateTimeFormat ?? string.Empty;
-            set => _dateTimeFormat = (string.IsNullOrEmpty(value)) ? null : value;
+            set => _dateTimeFormat = (StringUtils.IsNullOrEmpty(value)) ? null : value;
         }
 
         /// <summary>
@@ -162,7 +162,7 @@ namespace Newtonsoft.Json.Converters
 
             string? dateText = reader.Value?.ToString();
 
-            if (string.IsNullOrEmpty(dateText) && nullable)
+            if (StringUtils.IsNullOrEmpty(dateText) && nullable)
             {
                 return null;
             }
@@ -170,7 +170,7 @@ namespace Newtonsoft.Json.Converters
 #if HAVE_DATE_TIME_OFFSET
             if (t == typeof(DateTimeOffset))
             {
-                if (!string.IsNullOrEmpty(_dateTimeFormat))
+                if (!StringUtils.IsNullOrEmpty(_dateTimeFormat))
                 {
                     return DateTimeOffset.ParseExact(dateText, _dateTimeFormat, Culture, _dateTimeStyles);
                 }
@@ -181,7 +181,7 @@ namespace Newtonsoft.Json.Converters
             }
 #endif
 
-            if (!string.IsNullOrEmpty(_dateTimeFormat))
+            if (!StringUtils.IsNullOrEmpty(_dateTimeFormat))
             {
                 return DateTime.ParseExact(dateText, _dateTimeFormat, Culture, _dateTimeStyles);
             }
diff --git a/Src/Newtonsoft.Json/Converters/StringEnumConverter.cs b/Src/Newtonsoft.Json/Converters/StringEnumConverter.cs
index 550c02d9..9ba6b632 100644
--- a/Src/Newtonsoft.Json/Converters/StringEnumConverter.cs
+++ b/Src/Newtonsoft.Json/Converters/StringEnumConverter.cs
@@ -230,7 +230,7 @@ namespace Newtonsoft.Json.Converters
                 {
                     string? enumText = reader.Value?.ToString();
 
-                    if (string.IsNullOrEmpty(enumText) && isNullable)
+                    if (StringUtils.IsNullOrEmpty(enumText) && isNullable)
                     {
                         return null;
                     }
diff --git a/Src/Newtonsoft.Json/Converters/XmlNodeConverter.cs b/Src/Newtonsoft.Json/Converters/XmlNodeConverter.cs
index c3205ece..2abb677a 100644
--- a/Src/Newtonsoft.Json/Converters/XmlNodeConverter.cs
+++ b/Src/Newtonsoft.Json/Converters/XmlNodeConverter.cs
@@ -882,9 +882,9 @@ namespace Newtonsoft.Json.Converters
 
         private bool HasImplicitNamespaceAttribute(string namespaceUri)
         {
-            if (!string.IsNullOrEmpty(namespaceUri) && namespaceUri != ParentNode?.NamespaceUri)
+            if (!StringUtils.IsNullOrEmpty(namespaceUri) && namespaceUri != ParentNode?.NamespaceUri)
             {
-                if (string.IsNullOrEmpty(GetPrefixOfNamespace(namespaceUri)))
+                if (StringUtils.IsNullOrEmpty(GetPrefixOfNamespace(namespaceUri)))
                 {
                     bool namespaceDeclared = false;
 
@@ -892,7 +892,7 @@ namespace Newtonsoft.Json.Converters
                     {
                         foreach (XAttribute attribute in Element.Attributes())
                         {
-                            if (attribute.Name.LocalName == "xmlns" && string.IsNullOrEmpty(attribute.Name.NamespaceName) && attribute.Value == namespaceUri)
+                            if (attribute.Name.LocalName == "xmlns" && StringUtils.IsNullOrEmpty(attribute.Name.NamespaceName) && attribute.Value == namespaceUri)
                             {
                                 namespaceDeclared = true;
                             }
@@ -1072,7 +1072,7 @@ namespace Newtonsoft.Json.Converters
                 ? null
                 : manager.LookupPrefix(node.NamespaceUri);
 
-            if (!string.IsNullOrEmpty(prefix))
+            if (!StringUtils.IsNullOrEmpty(prefix))
             {
                 return prefix + ":" + XmlConvert.DecodeName(node.LocalName);
             }
@@ -1405,17 +1405,17 @@ namespace Newtonsoft.Json.Converters
                     writer.WritePropertyName(GetPropertyName(node, manager));
                     writer.WriteStartObject();
 
-                    if (!string.IsNullOrEmpty(declaration.Version))
+                    if (!StringUtils.IsNullOrEmpty(declaration.Version))
                     {
                         writer.WritePropertyName("@version");
                         writer.WriteValue(declaration.Version);
                     }
-                    if (!string.IsNullOrEmpty(declaration.Encoding))
+                    if (!StringUtils.IsNullOrEmpty(declaration.Encoding))
                     {
                         writer.WritePropertyName("@encoding");
                         writer.WriteValue(declaration.Encoding);
                     }
-                    if (!string.IsNullOrEmpty(declaration.Standalone))
+                    if (!StringUtils.IsNullOrEmpty(declaration.Standalone))
                     {
                         writer.WritePropertyName("@standalone");
                         writer.WriteValue(declaration.Standalone);
@@ -1428,22 +1428,22 @@ namespace Newtonsoft.Json.Converters
                     writer.WritePropertyName(GetPropertyName(node, manager));
                     writer.WriteStartObject();
 
-                    if (!string.IsNullOrEmpty(documentType.Name))
+                    if (!StringUtils.IsNullOrEmpty(documentType.Name))
                     {
                         writer.WritePropertyName("@name");
                         writer.WriteValue(documentType.Name);
                     }
-                    if (!string.IsNullOrEmpty(documentType.Public))
+                    if (!StringUtils.IsNullOrEmpty(documentType.Public))
                     {
                         writer.WritePropertyName("@public");
                         writer.WriteValue(documentType.Public);
                     }
-                    if (!string.IsNullOrEmpty(documentType.System))
+                    if (!StringUtils.IsNullOrEmpty(documentType.System))
                     {
                         writer.WritePropertyName("@system");
                         writer.WriteValue(documentType.System);
                     }
-                    if (!string.IsNullOrEmpty(documentType.InternalSubset))
+                    if (!StringUtils.IsNullOrEmpty(documentType.InternalSubset))
                     {
                         writer.WritePropertyName("@internalSubset");
                         writer.WriteValue(documentType.InternalSubset);
@@ -1537,7 +1537,7 @@ namespace Newtonsoft.Json.Converters
                 throw JsonSerializationException.Create(reader, "Unexpected type when converting XML: " + objectType);
             }
 
-            if (!string.IsNullOrEmpty(DeserializeRootElementName))
+            if (!StringUtils.IsNullOrEmpty(DeserializeRootElementName))
             {
                 ReadElement(reader, document, rootNode, DeserializeRootElementName, manager);
             }
@@ -1586,7 +1586,7 @@ namespace Newtonsoft.Json.Converters
                         return;
                     default:
                         // processing instructions and the xml declaration start with ?
-                        if (!string.IsNullOrEmpty(propertyName) && propertyName[0] == '?')
+                        if (!StringUtils.IsNullOrEmpty(propertyName) && propertyName[0] == '?')
                         {
                             CreateInstruction(reader, document, currentNode, propertyName);
                             return;
@@ -1616,7 +1616,7 @@ namespace Newtonsoft.Json.Converters
 
         private void ReadElement(JsonReader reader, IXmlDocument document, IXmlNode currentNode, string propertyName, XmlNamespaceManager manager)
         {
-            if (string.IsNullOrEmpty(propertyName))
+            if (StringUtils.IsNullOrEmpty(propertyName))
             {
                 throw JsonSerializationException.Create(reader, "XmlNodeConverter cannot convert JSON with an empty property name to XML.");
             }
@@ -1685,7 +1685,7 @@ namespace Newtonsoft.Json.Converters
                     string encodedName = XmlConvert.EncodeName(nameValue.Key);
                     string? attributePrefix = MiscellaneousUtils.GetPrefix(nameValue.Key);
 
-                    IXmlNode attribute = (!string.IsNullOrEmpty(attributePrefix)) ? document.CreateAttribute(encodedName, manager.LookupNamespace(attributePrefix) ?? string.Empty, nameValue.Value) : document.CreateAttribute(encodedName, nameValue.Value);
+                    IXmlNode attribute = (!StringUtils.IsNullOrEmpty(attributePrefix)) ? document.CreateAttribute(encodedName, manager.LookupNamespace(attributePrefix) ?? string.Empty, nameValue.Value) : document.CreateAttribute(encodedName, nameValue.Value);
 
                     element.SetAttributeNode(attribute);
                 }
@@ -1733,7 +1733,7 @@ namespace Newtonsoft.Json.Converters
             string encodedName = XmlConvert.EncodeName(attributeName);
             string? attributeValue = ConvertTokenToXmlValue(reader);
 
-            IXmlNode attribute = (!string.IsNullOrEmpty(attributePrefix))
+            IXmlNode attribute = (!StringUtils.IsNullOrEmpty(attributePrefix))
                 ? document.CreateAttribute(encodedName, manager.LookupNamespace(attributePrefix), attributeValue)
                 : document.CreateAttribute(encodedName, attributeValue);
 
@@ -1876,7 +1876,7 @@ namespace Newtonsoft.Json.Converters
                     case JsonToken.PropertyName:
                         string attributeName = reader.Value!.ToString();
 
-                        if (!string.IsNullOrEmpty(attributeName))
+                        if (!StringUtils.IsNullOrEmpty(attributeName))
                         {
                             char firstChar = attributeName[0];
                             string? attributeValue;
@@ -2058,9 +2058,9 @@ namespace Newtonsoft.Json.Converters
         private IXmlElement CreateElement(string elementName, IXmlDocument document, string? elementPrefix, XmlNamespaceManager manager)
         {
             string encodeName = EncodeSpecialCharacters ? XmlConvert.EncodeLocalName(elementName) : XmlConvert.EncodeName(elementName);
-            string ns = string.IsNullOrEmpty(elementPrefix) ? manager.DefaultNamespace : manager.LookupNamespace(elementPrefix);
+            string ns = StringUtils.IsNullOrEmpty(elementPrefix) ? manager.DefaultNamespace : manager.LookupNamespace(elementPrefix);
 
-            IXmlElement element = (!string.IsNullOrEmpty(ns)) ? document.CreateElement(encodeName, ns) : document.CreateElement(encodeName);
+            IXmlElement element = (!StringUtils.IsNullOrEmpty(ns)) ? document.CreateElement(encodeName, ns) : document.CreateElement(encodeName);
 
             return element;
         }
@@ -2092,7 +2092,7 @@ namespace Newtonsoft.Json.Converters
                             if (count == 1 && WriteArrayAttribute)
                             {
                                 MiscellaneousUtils.GetQualifiedNameParts(propertyName, out string? elementPrefix, out string localName);
-                                string ns = string.IsNullOrEmpty(elementPrefix) ? manager.DefaultNamespace : manager.LookupNamespace(elementPrefix);
+                                string ns = StringUtils.IsNullOrEmpty(elementPrefix) ? manager.DefaultNamespace : manager.LookupNamespace(elementPrefix);
 
                                 foreach (IXmlNode childNode in currentNode.ChildNodes)
                                 {
diff --git a/Src/Newtonsoft.Json/JsonReader.cs b/Src/Newtonsoft.Json/JsonReader.cs
index ba19d3d3..736ee0df 100644
--- a/Src/Newtonsoft.Json/JsonReader.cs
+++ b/Src/Newtonsoft.Json/JsonReader.cs
@@ -445,7 +445,7 @@ namespace Newtonsoft.Json
 
         internal int? ReadInt32String(string? s)
         {
-            if (string.IsNullOrEmpty(s))
+            if (StringUtils.IsNullOrEmpty(s))
             {
                 SetToken(JsonToken.Null, null, false);
                 return null;
@@ -656,7 +656,7 @@ namespace Newtonsoft.Json
 
         internal double? ReadDoubleString(string? s)
         {
-            if (string.IsNullOrEmpty(s))
+            if (StringUtils.IsNullOrEmpty(s))
             {
                 SetToken(JsonToken.Null, null, false);
                 return null;
@@ -715,7 +715,7 @@ namespace Newtonsoft.Json
 
         internal bool? ReadBooleanString(string? s)
         {
-            if (string.IsNullOrEmpty(s))
+            if (StringUtils.IsNullOrEmpty(s))
             {
                 SetToken(JsonToken.Null, null, false);
                 return null;
@@ -786,7 +786,7 @@ namespace Newtonsoft.Json
 
         internal decimal? ReadDecimalString(string? s)
         {
-            if (string.IsNullOrEmpty(s))
+            if (StringUtils.IsNullOrEmpty(s))
             {
                 SetToken(JsonToken.Null, null, false);
                 return null;
@@ -840,7 +840,7 @@ namespace Newtonsoft.Json
 
         internal DateTime? ReadDateTimeString(string? s)
         {
-            if (string.IsNullOrEmpty(s))
+            if (StringUtils.IsNullOrEmpty(s))
             {
                 SetToken(JsonToken.Null, null, false);
                 return null;
@@ -895,7 +895,7 @@ namespace Newtonsoft.Json
 
         internal DateTimeOffset? ReadDateTimeOffsetString(string? s)
         {
-            if (string.IsNullOrEmpty(s))
+            if (StringUtils.IsNullOrEmpty(s))
             {
                 SetToken(JsonToken.Null, null, false);
                 return null;
diff --git a/Src/Newtonsoft.Json/JsonTextReader.Async.cs b/Src/Newtonsoft.Json/JsonTextReader.Async.cs
index 443c3055..7963f5b9 100644
--- a/Src/Newtonsoft.Json/JsonTextReader.Async.cs
+++ b/Src/Newtonsoft.Json/JsonTextReader.Async.cs
@@ -111,7 +111,7 @@ namespace Newtonsoft.Json
 
         private async Task<bool> ParsePostValueAsync(bool ignoreComments, CancellationToken cancellationToken)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             while (true)
             {
@@ -196,7 +196,7 @@ namespace Newtonsoft.Json
 
         private async Task<bool> ReadFromFinishedAsync(CancellationToken cancellationToken)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             if (await EnsureCharsAsync(0, false, cancellationToken).ConfigureAwait(false))
             {
@@ -227,7 +227,7 @@ namespace Newtonsoft.Json
 
         private async Task<int> ReadDataAsync(bool append, int charsRequired, CancellationToken cancellationToken)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             if (_isEndOfFile)
             {
@@ -251,7 +251,7 @@ namespace Newtonsoft.Json
 
         private async Task<bool> ParseValueAsync(CancellationToken cancellationToken)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             while (true)
             {
@@ -382,7 +382,7 @@ namespace Newtonsoft.Json
 
         private async Task ReadStringIntoBufferAsync(char quote, CancellationToken cancellationToken)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             int charPos = _charPos;
             int initialPosition = _charPos;
@@ -600,7 +600,7 @@ namespace Newtonsoft.Json
 
         private async Task<bool> ParseObjectAsync(CancellationToken cancellationToken)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             while (true)
             {
@@ -659,7 +659,7 @@ namespace Newtonsoft.Json
 
         private async Task ParseCommentAsync(bool setToken, CancellationToken cancellationToken)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             // should have already parsed / character before reaching this method
             _charPos++;
@@ -757,7 +757,7 @@ namespace Newtonsoft.Json
 
         private async Task EatWhitespaceAsync(CancellationToken cancellationToken)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             while (true)
             {
@@ -815,7 +815,7 @@ namespace Newtonsoft.Json
 
         private async Task<bool> MatchValueWithTrailingSeparatorAsync(string value, CancellationToken cancellationToken)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             // will match value and then move to the next character, checking that it is a separator character
             if (!await MatchValueAsync(value, cancellationToken).ConfigureAwait(false))
@@ -860,7 +860,7 @@ namespace Newtonsoft.Json
 
         private async Task ParseConstructorAsync(CancellationToken cancellationToken)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             if (await MatchValueWithTrailingSeparatorAsync("new", cancellationToken).ConfigureAwait(false))
             {
@@ -960,7 +960,7 @@ namespace Newtonsoft.Json
 
         private async Task ParseNumberAsync(ReadType readType, CancellationToken cancellationToken)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             ShiftBufferIfNeeded();
 
@@ -979,7 +979,7 @@ namespace Newtonsoft.Json
 
         private async Task<bool> ParsePropertyAsync(CancellationToken cancellationToken)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             char firstChar = _chars[_charPos];
             char quoteChar;
@@ -1033,7 +1033,7 @@ namespace Newtonsoft.Json
 
         private async Task ReadNumberIntoBufferAsync(CancellationToken cancellationToken)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             int charPos = _charPos;
 
@@ -1069,7 +1069,7 @@ namespace Newtonsoft.Json
 
         private async Task ParseUnquotedPropertyAsync(CancellationToken cancellationToken)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             int initialPosition = _charPos;
 
@@ -1120,7 +1120,7 @@ namespace Newtonsoft.Json
 
         private async Task HandleNullAsync(CancellationToken cancellationToken)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             if (await EnsureCharsAsync(1, true, cancellationToken).ConfigureAwait(false))
             {
@@ -1140,7 +1140,7 @@ namespace Newtonsoft.Json
 
         private async Task ReadFinishedAsync(CancellationToken cancellationToken)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             if (await EnsureCharsAsync(0, false, cancellationToken).ConfigureAwait(false))
             {
@@ -1167,7 +1167,7 @@ namespace Newtonsoft.Json
         private async Task<object?> ReadStringValueAsync(ReadType readType, CancellationToken cancellationToken)
         {
             EnsureBuffer();
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             switch (_currentState)
             {
@@ -1303,7 +1303,7 @@ namespace Newtonsoft.Json
         private async Task<object?> ReadNumberValueAsync(ReadType readType, CancellationToken cancellationToken)
         {
             EnsureBuffer();
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             switch (_currentState)
             {
@@ -1430,7 +1430,7 @@ namespace Newtonsoft.Json
         internal async Task<bool?> DoReadAsBooleanAsync(CancellationToken cancellationToken)
         {
             EnsureBuffer();
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             switch (_currentState)
             {
@@ -1566,7 +1566,7 @@ namespace Newtonsoft.Json
         internal async Task<byte[]?> DoReadAsBytesAsync(CancellationToken cancellationToken)
         {
             EnsureBuffer();
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             bool isWrapped = false;
 
diff --git a/Src/Newtonsoft.Json/JsonTextReader.cs b/Src/Newtonsoft.Json/JsonTextReader.cs
index b95cb821..0ef5b0e5 100644
--- a/Src/Newtonsoft.Json/JsonTextReader.cs
+++ b/Src/Newtonsoft.Json/JsonTextReader.cs
@@ -138,7 +138,7 @@ namespace Newtonsoft.Json
 
         private void SetNewLine(bool hasNextChar)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             if (hasNextChar && _chars[_charPos] == StringUtils.LineFeed)
             {
@@ -252,7 +252,7 @@ namespace Newtonsoft.Json
 
         private void ShiftBufferIfNeeded()
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             // once in the last 10% of the buffer, or buffer is already very large then
             // shift the remaining content to the start to avoid unnecessarily increasing
@@ -280,7 +280,7 @@ namespace Newtonsoft.Json
 
         private void PrepareBufferForReadData(bool append, int charsRequired)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             // char buffer is full
             if (_charsUsed + charsRequired >= _chars.Length - 1)
@@ -345,7 +345,7 @@ namespace Newtonsoft.Json
             }
 
             PrepareBufferForReadData(append, charsRequired);
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             int attemptCharReadCount = _chars.Length - _charsUsed - 1;
 
@@ -414,7 +414,7 @@ namespace Newtonsoft.Json
         public override bool Read()
         {
             EnsureBuffer();
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             while (true)
             {
@@ -497,7 +497,7 @@ namespace Newtonsoft.Json
         public override byte[]? ReadAsBytes()
         {
             EnsureBuffer();
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             bool isWrapped = false;
 
@@ -603,7 +603,7 @@ namespace Newtonsoft.Json
         private object? ReadStringValue(ReadType readType)
         {
             EnsureBuffer();
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             switch (_currentState)
             {
@@ -770,7 +770,7 @@ namespace Newtonsoft.Json
         public override bool? ReadAsBoolean()
         {
             EnsureBuffer();
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             switch (_currentState)
             {
@@ -908,7 +908,7 @@ namespace Newtonsoft.Json
         private object? ReadNumberValue(ReadType readType)
         {
             EnsureBuffer();
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             switch (_currentState)
             {
@@ -1062,7 +1062,7 @@ namespace Newtonsoft.Json
 
         private void HandleNull()
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             if (EnsureChars(1, true))
             {
@@ -1084,7 +1084,7 @@ namespace Newtonsoft.Json
 
         private void ReadFinished()
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             if (EnsureChars(0, false))
             {
@@ -1135,7 +1135,7 @@ namespace Newtonsoft.Json
 
         private void ReadStringIntoBuffer(char quote)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             int charPos = _charPos;
             int initialPosition = _charPos;
@@ -1290,7 +1290,7 @@ namespace Newtonsoft.Json
 
         private void FinishReadStringIntoBuffer(int charPos, int initialPosition, int lastWritePosition)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             if (initialPosition == lastWritePosition)
             {
@@ -1313,7 +1313,7 @@ namespace Newtonsoft.Json
 
         private void WriteCharToBuffer(char writeChar, int lastWritePosition, int writeToPosition)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             if (writeToPosition > lastWritePosition)
             {
@@ -1325,7 +1325,7 @@ namespace Newtonsoft.Json
 
         private char ConvertUnicode(bool enoughChars)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             if (enoughChars)
             {
@@ -1353,7 +1353,7 @@ namespace Newtonsoft.Json
 
         private void ReadNumberIntoBuffer()
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             int charPos = _charPos;
 
@@ -1439,7 +1439,7 @@ namespace Newtonsoft.Json
 
         private bool ParsePostValue(bool ignoreComments)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             while (true)
             {
@@ -1521,7 +1521,7 @@ namespace Newtonsoft.Json
 
         private bool ParseObject()
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             while (true)
             {
@@ -1577,7 +1577,7 @@ namespace Newtonsoft.Json
 
         private bool ParseProperty()
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             char firstChar = _chars[_charPos];
             char quoteChar;
@@ -1640,7 +1640,7 @@ namespace Newtonsoft.Json
 
         private void ParseUnquotedProperty()
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             int initialPosition = _charPos;
 
@@ -1673,7 +1673,7 @@ namespace Newtonsoft.Json
 
         private bool ReadUnquotedPropertyReportIfDone(char currentChar, int initialPosition)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             if (ValidIdentifierChar(currentChar))
             {
@@ -1692,7 +1692,7 @@ namespace Newtonsoft.Json
 
         private bool ParseValue()
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             while (true)
             {
@@ -1834,7 +1834,7 @@ namespace Newtonsoft.Json
 
         private void EatWhitespace()
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             while (true)
             {
@@ -1877,7 +1877,7 @@ namespace Newtonsoft.Json
 
         private void ParseConstructor()
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             if (MatchValueWithTrailingSeparator("new"))
             {
@@ -1963,7 +1963,7 @@ namespace Newtonsoft.Json
         private void ParseNumber(ReadType readType)
         {
             ShiftBufferIfNeeded();
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             char firstChar = _chars[_charPos];
             int initialPosition = _charPos;
@@ -1975,7 +1975,7 @@ namespace Newtonsoft.Json
 
         private void ParseReadNumber(ReadType readType, char firstChar, int initialPosition)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             // set state to PostValue now so that if there is an error parsing the number then the reader can continue
             SetPostValueState(true);
@@ -2257,7 +2257,7 @@ namespace Newtonsoft.Json
 
         private void ParseComment(bool setToken)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             // should have already parsed / character before reaching this method
             _charPos++;
@@ -2364,7 +2364,7 @@ namespace Newtonsoft.Json
 
         private bool MatchValue(bool enoughChars, string value)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             if (!enoughChars)
             {
@@ -2388,7 +2388,7 @@ namespace Newtonsoft.Json
 
         private bool MatchValueWithTrailingSeparator(string value)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             // will match value and then move to the next character, checking that it is a separator character
             bool match = MatchValue(value);
@@ -2408,7 +2408,7 @@ namespace Newtonsoft.Json
 
         private bool IsSeparator(char c)
         {
-            Debug.Assert(_chars != null);
+            MiscellaneousUtils.Assert(_chars != null);
 
             switch (c)
             {
diff --git a/Src/Newtonsoft.Json/JsonTextWriter.Async.cs b/Src/Newtonsoft.Json/JsonTextWriter.Async.cs
index 89ae0ab7..c1c763e9 100644
--- a/Src/Newtonsoft.Json/JsonTextWriter.Async.cs
+++ b/Src/Newtonsoft.Json/JsonTextWriter.Async.cs
@@ -165,7 +165,7 @@ namespace Newtonsoft.Json
             int currentIndentCount = Top * _indentation;
 
             int newLineLen = SetIndentChars();
-            Debug.Assert(_indentChars != null);
+            MiscellaneousUtils.Assert(_indentChars != null);
 
             if (currentIndentCount <= IndentCharBufferSize)
             {
@@ -177,7 +177,7 @@ namespace Newtonsoft.Json
 
         private async Task WriteIndentAsync(int currentIndentCount, int newLineLen, CancellationToken cancellationToken)
         {
-            Debug.Assert(_indentChars != null);
+            MiscellaneousUtils.Assert(_indentChars != null);
 
             await _writer.WriteAsync(_indentChars, 0, newLineLen + Math.Min(currentIndentCount, IndentCharBufferSize), cancellationToken).ConfigureAwait(false);
 
@@ -657,7 +657,7 @@ namespace Newtonsoft.Json
             await InternalWriteValueAsync(JsonToken.Date, cancellationToken).ConfigureAwait(false);
             value = DateTimeUtils.EnsureDateTime(value, DateTimeZoneHandling);
 
-            if (string.IsNullOrEmpty(DateFormatString))
+            if (StringUtils.IsNullOrEmpty(DateFormatString))
             {
                 int length = WriteValueToBuffer(value);
 
@@ -706,7 +706,7 @@ namespace Newtonsoft.Json
         {
             await InternalWriteValueAsync(JsonToken.Date, cancellationToken).ConfigureAwait(false);
 
-            if (string.IsNullOrEmpty(DateFormatString))
+            if (StringUtils.IsNullOrEmpty(DateFormatString))
             {
                 int length = WriteValueToBuffer(value);
 
diff --git a/Src/Newtonsoft.Json/JsonTextWriter.cs b/Src/Newtonsoft.Json/JsonTextWriter.cs
index 2bb21ee8..b08dfb48 100644
--- a/Src/Newtonsoft.Json/JsonTextWriter.cs
+++ b/Src/Newtonsoft.Json/JsonTextWriter.cs
@@ -633,7 +633,7 @@ namespace Newtonsoft.Json
             InternalWriteValue(JsonToken.Date);
             value = DateTimeUtils.EnsureDateTime(value, DateTimeZoneHandling);
 
-            if (string.IsNullOrEmpty(DateFormatString))
+            if (StringUtils.IsNullOrEmpty(DateFormatString))
             {
                 int length = WriteValueToBuffer(value);
 
@@ -650,7 +650,7 @@ namespace Newtonsoft.Json
         private int WriteValueToBuffer(DateTime value)
         {
             EnsureWriteBuffer();
-            Debug.Assert(_writeBuffer != null);
+            MiscellaneousUtils.Assert(_writeBuffer != null);
 
             int pos = 0;
             _writeBuffer[pos++] = _quoteChar;
@@ -688,7 +688,7 @@ namespace Newtonsoft.Json
         {
             InternalWriteValue(JsonToken.Date);
 
-            if (string.IsNullOrEmpty(DateFormatString))
+            if (StringUtils.IsNullOrEmpty(DateFormatString))
             {
                 int length = WriteValueToBuffer(value);
 
@@ -705,7 +705,7 @@ namespace Newtonsoft.Json
         private int WriteValueToBuffer(DateTimeOffset value)
         {
             EnsureWriteBuffer();
-            Debug.Assert(_writeBuffer != null);
+            MiscellaneousUtils.Assert(_writeBuffer != null);
 
             int pos = 0;
             _writeBuffer[pos++] = _quoteChar;
@@ -842,7 +842,7 @@ namespace Newtonsoft.Json
             }
 
             EnsureWriteBuffer();
-            Debug.Assert(_writeBuffer != null);
+            MiscellaneousUtils.Assert(_writeBuffer != null);
 
             int totalLength = MathUtils.IntLength(value);
 
@@ -894,7 +894,7 @@ namespace Newtonsoft.Json
         private int WriteNumberToBuffer(uint value, bool negative)
         {
             EnsureWriteBuffer();
-            Debug.Assert(_writeBuffer != null);
+            MiscellaneousUtils.Assert(_writeBuffer != null);
 
             int totalLength = MathUtils.IntLength(value);
 
diff --git a/Src/Newtonsoft.Json/Linq/JContainer.Async.cs b/Src/Newtonsoft.Json/Linq/JContainer.Async.cs
index 455ed8ff..beb67afd 100644
--- a/Src/Newtonsoft.Json/Linq/JContainer.Async.cs
+++ b/Src/Newtonsoft.Json/Linq/JContainer.Async.cs
@@ -72,7 +72,7 @@ namespace Newtonsoft.Json.Linq
                     parent = parent.Parent;
                 }
 
-                Debug.Assert(parent != null);
+                MiscellaneousUtils.Assert(parent != null);
 
                 switch (reader.TokenType)
                 {
diff --git a/Src/Newtonsoft.Json/Linq/JContainer.cs b/Src/Newtonsoft.Json/Linq/JContainer.cs
index 81833940..4b30e44e 100644
--- a/Src/Newtonsoft.Json/Linq/JContainer.cs
+++ b/Src/Newtonsoft.Json/Linq/JContainer.cs
@@ -765,7 +765,7 @@ namespace Newtonsoft.Json.Linq
                     parent = parent.Parent;
                 }
 
-                Debug.Assert(parent != null);
+                MiscellaneousUtils.Assert(parent != null);
 
                 switch (r.TokenType)
                 {
diff --git a/Src/Newtonsoft.Json/Linq/JProperty.cs b/Src/Newtonsoft.Json/Linq/JProperty.cs
index 5e2b998c..3805bd60 100644
--- a/Src/Newtonsoft.Json/Linq/JProperty.cs
+++ b/Src/Newtonsoft.Json/Linq/JProperty.cs
@@ -122,7 +122,7 @@ namespace Newtonsoft.Json.Linq
                         throw new IndexOutOfRangeException();
                     }
 
-                    Debug.Assert(_token != null);
+                    MiscellaneousUtils.Assert(_token != null);
                     return _token;
                 }
                 set
diff --git a/Src/Newtonsoft.Json/Linq/JTokenReader.cs b/Src/Newtonsoft.Json/Linq/JTokenReader.cs
index aad1150c..03480570 100644
--- a/Src/Newtonsoft.Json/Linq/JTokenReader.cs
+++ b/Src/Newtonsoft.Json/Linq/JTokenReader.cs
@@ -315,9 +315,9 @@ namespace Newtonsoft.Json.Linq
                     _initialPath = _root.Path;
                 }
 
-                if (!string.IsNullOrEmpty(_initialPath))
+                if (!StringUtils.IsNullOrEmpty(_initialPath))
                 {
-                    if (string.IsNullOrEmpty(path))
+                    if (StringUtils.IsNullOrEmpty(path))
                     {
                         return _initialPath;
                     }
diff --git a/Src/Newtonsoft.Json/Linq/JValue.cs b/Src/Newtonsoft.Json/Linq/JValue.cs
index ff089c55..d5aa1eff 100644
--- a/Src/Newtonsoft.Json/Linq/JValue.cs
+++ b/Src/Newtonsoft.Json/Linq/JValue.cs
@@ -356,7 +356,7 @@ namespace Newtonsoft.Json.Linq
                     }
 
                     byte[]? bytesA = objA as byte[];
-                    Debug.Assert(bytesA != null);
+                    MiscellaneousUtils.Assert(bytesA != null);
 
                     return MiscellaneousUtils.ByteArrayCompare(bytesA!, bytesB);
                 case JTokenType.Guid:
diff --git a/Src/Newtonsoft.Json/Linq/JsonPath/QueryExpression.cs b/Src/Newtonsoft.Json/Linq/JsonPath/QueryExpression.cs
index 69eee36c..f7bf1d5f 100644
--- a/Src/Newtonsoft.Json/Linq/JsonPath/QueryExpression.cs
+++ b/Src/Newtonsoft.Json/Linq/JsonPath/QueryExpression.cs
@@ -294,8 +294,8 @@ namespace Newtonsoft.Json.Linq.JsonPath
 
         internal static bool EqualsWithStrictMatch(JValue value, JValue queryValue)
         {
-            Debug.Assert(value != null);
-            Debug.Assert(queryValue != null);
+            MiscellaneousUtils.Assert(value != null);
+            MiscellaneousUtils.Assert(queryValue != null);
 
             // Handle comparing an integer with a float
             // e.g. Comparing 1 and 1.0
diff --git a/Src/Newtonsoft.Json/Schema/JsonSchemaBuilder.cs b/Src/Newtonsoft.Json/Schema/JsonSchemaBuilder.cs
index c87ffd6f..445d3a6f 100644
--- a/Src/Newtonsoft.Json/Schema/JsonSchemaBuilder.cs
+++ b/Src/Newtonsoft.Json/Schema/JsonSchemaBuilder.cs
@@ -221,7 +221,7 @@ namespace Newtonsoft.Json.Schema
             }
 
             string location = token.Path.Replace(".", "/").Replace("[", "/").Replace("]", string.Empty);
-            if (!string.IsNullOrEmpty(location))
+            if (!StringUtils.IsNullOrEmpty(location))
             {
                 location = "/" + location;
             }
diff --git a/Src/Newtonsoft.Json/Schema/JsonSchemaGenerator.cs b/Src/Newtonsoft.Json/Schema/JsonSchemaGenerator.cs
index e0b3e406..7cdab611 100644
--- a/Src/Newtonsoft.Json/Schema/JsonSchemaGenerator.cs
+++ b/Src/Newtonsoft.Json/Schema/JsonSchemaGenerator.cs
@@ -175,7 +175,7 @@ namespace Newtonsoft.Json.Schema
         {
             JsonContainerAttribute containerAttribute = JsonTypeReflector.GetCachedAttribute<JsonContainerAttribute>(type);
 
-            if (!string.IsNullOrEmpty(containerAttribute?.Title))
+            if (!StringUtils.IsNullOrEmpty(containerAttribute?.Title))
             {
                 return containerAttribute.Title;
             }
@@ -187,7 +187,7 @@ namespace Newtonsoft.Json.Schema
         {
             JsonContainerAttribute containerAttribute = JsonTypeReflector.GetCachedAttribute<JsonContainerAttribute>(type);
 
-            if (!string.IsNullOrEmpty(containerAttribute?.Description))
+            if (!StringUtils.IsNullOrEmpty(containerAttribute?.Description))
             {
                 return containerAttribute.Description;
             }
@@ -204,7 +204,7 @@ namespace Newtonsoft.Json.Schema
         {
             JsonContainerAttribute containerAttribute = JsonTypeReflector.GetCachedAttribute<JsonContainerAttribute>(type);
 
-            if (!string.IsNullOrEmpty(containerAttribute?.Id))
+            if (!StringUtils.IsNullOrEmpty(containerAttribute?.Id))
             {
                 return containerAttribute.Id;
             }
@@ -232,7 +232,7 @@ namespace Newtonsoft.Json.Schema
             string resolvedId = GetTypeId(type, false);
             string explicitId = GetTypeId(type, true);
 
-            if (!string.IsNullOrEmpty(resolvedId))
+            if (!StringUtils.IsNullOrEmpty(resolvedId))
             {
                 JsonSchema resolvedSchema = _resolver.GetSchema(resolvedId);
                 if (resolvedSchema != null)
diff --git a/Src/Newtonsoft.Json/Serialization/JsonArrayContract.cs b/Src/Newtonsoft.Json/Serialization/JsonArrayContract.cs
index e60030d7..a2ce9dac 100644
--- a/Src/Newtonsoft.Json/Serialization/JsonArrayContract.cs
+++ b/Src/Newtonsoft.Json/Serialization/JsonArrayContract.cs
@@ -273,7 +273,7 @@ namespace Newtonsoft.Json.Serialization
         {
             if (_genericWrapperCreator == null)
             {
-                Debug.Assert(_genericCollectionDefinitionType != null);
+                MiscellaneousUtils.Assert(_genericCollectionDefinitionType != null);
 
                 _genericWrapperType = typeof(CollectionWrapper<>).MakeGenericType(CollectionItemType);
 
diff --git a/Src/Newtonsoft.Json/Serialization/JsonProperty.cs b/Src/Newtonsoft.Json/Serialization/JsonProperty.cs
index 1979c599..183a5a72 100644
--- a/Src/Newtonsoft.Json/Serialization/JsonProperty.cs
+++ b/Src/Newtonsoft.Json/Serialization/JsonProperty.cs
@@ -307,7 +307,7 @@ namespace Newtonsoft.Json.Serialization
         internal void WritePropertyName(JsonWriter writer)
         {
             string? propertyName = PropertyName;
-            Debug.Assert(propertyName != null);
+            MiscellaneousUtils.Assert(propertyName != null);
 
             if (_skipPropertyNameEscape)
             {
diff --git a/Src/Newtonsoft.Json/Serialization/JsonPropertyCollection.cs b/Src/Newtonsoft.Json/Serialization/JsonPropertyCollection.cs
index d631a83f..8b3d201c 100644
--- a/Src/Newtonsoft.Json/Serialization/JsonPropertyCollection.cs
+++ b/Src/Newtonsoft.Json/Serialization/JsonPropertyCollection.cs
@@ -73,7 +73,7 @@ namespace Newtonsoft.Json.Serialization
         /// <param name="property">The property to add to the collection.</param>
         public void AddProperty(JsonProperty property)
         {
-            Debug.Assert(property.PropertyName != null);
+            MiscellaneousUtils.Assert(property.PropertyName != null);
 
             if (Contains(property.PropertyName))
             {
diff --git a/Src/Newtonsoft.Json/Serialization/JsonSerializerInternalReader.cs b/Src/Newtonsoft.Json/Serialization/JsonSerializerInternalReader.cs
index 5cb82550..97229a1b 100644
--- a/Src/Newtonsoft.Json/Serialization/JsonSerializerInternalReader.cs
+++ b/Src/Newtonsoft.Json/Serialization/JsonSerializerInternalReader.cs
@@ -351,7 +351,7 @@ namespace Newtonsoft.Json.Serialization
 
         private static bool CoerceEmptyStringToNull(Type? objectType, JsonContract? contract, string s)
         {
-            return string.IsNullOrEmpty(s) && objectType != null && objectType != typeof(string) && objectType != typeof(object) && contract != null && contract.IsNullable;
+            return StringUtils.IsNullOrEmpty(s) && objectType != null && objectType != typeof(string) && objectType != typeof(object) && contract != null && contract.IsNullable;
         }
 
         internal string GetExpectedDescription(JsonContract contract)
@@ -464,8 +464,8 @@ namespace Newtonsoft.Json.Serialization
                 return CreateJObject(reader);
             }
 
-            Debug.Assert(resolvedObjectType != null);
-            Debug.Assert(contract != null);
+            MiscellaneousUtils.Assert(resolvedObjectType != null);
+            MiscellaneousUtils.Assert(contract != null);
 
             switch (contract.ContractType)
             {
@@ -840,8 +840,8 @@ namespace Newtonsoft.Json.Serialization
                 return CreateJToken(reader, contract);
             }
 
-            Debug.Assert(objectType != null);
-            Debug.Assert(contract != null);
+            MiscellaneousUtils.Assert(objectType != null);
+            MiscellaneousUtils.Assert(contract != null);
 
             JsonArrayContract arrayContract = EnsureArrayContract(reader, objectType, contract);
 
@@ -936,7 +936,7 @@ namespace Newtonsoft.Json.Serialization
                 return value;
             }
 
-            Debug.Assert(contract != null);
+            MiscellaneousUtils.Assert(contract != null);
             Type? valueType = ReflectionUtils.GetObjectType(value);
 
             // type of value and type of target don't match
diff --git a/Src/Newtonsoft.Json/Serialization/JsonSerializerInternalWriter.cs b/Src/Newtonsoft.Json/Serialization/JsonSerializerInternalWriter.cs
index fc0ded0b..2a21a4f7 100644
--- a/Src/Newtonsoft.Json/Serialization/JsonSerializerInternalWriter.cs
+++ b/Src/Newtonsoft.Json/Serialization/JsonSerializerInternalWriter.cs
@@ -159,7 +159,7 @@ namespace Newtonsoft.Json.Serialization
                 return;
             }
 
-            Debug.Assert(valueContract != null);
+            MiscellaneousUtils.Assert(valueContract != null);
 
             JsonConverter? converter =
                 member?.Converter ??
@@ -252,7 +252,7 @@ namespace Newtonsoft.Json.Serialization
                 return false;
             }
 
-            Debug.Assert(valueContract != null);
+            MiscellaneousUtils.Assert(valueContract != null);
 
             if (valueContract.ContractType == JsonContractType.Primitive || valueContract.ContractType == JsonContractType.String)
             {
@@ -304,7 +304,7 @@ namespace Newtonsoft.Json.Serialization
                 return true;
             }
 
-            Debug.Assert(contract != null);
+            MiscellaneousUtils.Assert(contract != null);
 
             if (contract.ContractType == JsonContractType.Primitive || contract.ContractType == JsonContractType.String)
             {
diff --git a/Src/Newtonsoft.Json/Utilities/AsyncUtils.cs b/Src/Newtonsoft.Json/Utilities/AsyncUtils.cs
index ebcd7b05..80ff463a 100644
--- a/Src/Newtonsoft.Json/Utilities/AsyncUtils.cs
+++ b/Src/Newtonsoft.Json/Utilities/AsyncUtils.cs
@@ -54,13 +54,13 @@ namespace Newtonsoft.Json.Utilities
         // previous frameworks.
         public static Task FromCanceled(this CancellationToken cancellationToken)
         {
-            Debug.Assert(cancellationToken.IsCancellationRequested);
+            MiscellaneousUtils.Assert(cancellationToken.IsCancellationRequested);
             return new Task(() => {}, cancellationToken);
         }
 
         public static Task<T> FromCanceled<T>(this CancellationToken cancellationToken)
         {
-            Debug.Assert(cancellationToken.IsCancellationRequested);
+            MiscellaneousUtils.Assert(cancellationToken.IsCancellationRequested);
 #pragma warning disable CS8653 // A default expression introduces a null value for a type parameter.
             return new Task<T>(() => default, cancellationToken);
 #pragma warning restore CS8653 // A default expression introduces a null value for a type parameter.
@@ -73,25 +73,25 @@ namespace Newtonsoft.Json.Utilities
 
         public static Task WriteAsync(this TextWriter writer, char value, CancellationToken cancellationToken)
         {
-            Debug.Assert(writer != null);
+            MiscellaneousUtils.Assert(writer != null);
             return cancellationToken.IsCancellationRequested ? FromCanceled(cancellationToken) : writer.WriteAsync(value);
         }
 
         public static Task WriteAsync(this TextWriter writer, string? value, CancellationToken cancellationToken)
         {
-            Debug.Assert(writer != null);
+            MiscellaneousUtils.Assert(writer != null);
             return cancellationToken.IsCancellationRequested ? FromCanceled(cancellationToken) : writer.WriteAsync(value);
         }
 
         public static Task WriteAsync(this TextWriter writer, char[] value, int start, int count, CancellationToken cancellationToken)
         {
-            Debug.Assert(writer != null);
+            MiscellaneousUtils.Assert(writer != null);
             return cancellationToken.IsCancellationRequested ? FromCanceled(cancellationToken) : writer.WriteAsync(value, start, count);
         }
 
         public static Task<int> ReadAsync(this TextReader reader, char[] buffer, int index, int count, CancellationToken cancellationToken)
         {
-            Debug.Assert(reader != null);
+            MiscellaneousUtils.Assert(reader != null);
             return cancellationToken.IsCancellationRequested ? FromCanceled<int>(cancellationToken) : reader.ReadAsync(buffer, index, count);
         }
 
diff --git a/Src/Newtonsoft.Json/Utilities/DateTimeUtils.cs b/Src/Newtonsoft.Json/Utilities/DateTimeUtils.cs
index c1cd79e8..0b4b3545 100644
--- a/Src/Newtonsoft.Json/Utilities/DateTimeUtils.cs
+++ b/Src/Newtonsoft.Json/Utilities/DateTimeUtils.cs
@@ -364,7 +364,7 @@ namespace Newtonsoft.Json.Utilities
                     }
                 }
 
-                if (!string.IsNullOrEmpty(dateFormatString))
+                if (!StringUtils.IsNullOrEmpty(dateFormatString))
                 {
                     if (TryParseDateTimeExact(s.ToString(), dateTimeZoneHandling, dateFormatString, culture, out dt))
                     {
@@ -400,7 +400,7 @@ namespace Newtonsoft.Json.Utilities
                     }
                 }
 
-                if (!string.IsNullOrEmpty(dateFormatString))
+                if (!StringUtils.IsNullOrEmpty(dateFormatString))
                 {
                     if (TryParseDateTimeExact(s, dateTimeZoneHandling, dateFormatString, culture, out dt))
                     {
@@ -437,7 +437,7 @@ namespace Newtonsoft.Json.Utilities
                     }
                 }
 
-                if (!string.IsNullOrEmpty(dateFormatString))
+                if (!StringUtils.IsNullOrEmpty(dateFormatString))
                 {
                     if (TryParseDateTimeOffsetExact(s.ToString(), dateFormatString, culture, out dt))
                     {
@@ -475,7 +475,7 @@ namespace Newtonsoft.Json.Utilities
                     }
                 }
 
-                if (!string.IsNullOrEmpty(dateFormatString))
+                if (!StringUtils.IsNullOrEmpty(dateFormatString))
                 {
                     if (TryParseDateTimeOffsetExact(s, dateFormatString, culture, out dt))
                     {
@@ -620,7 +620,7 @@ namespace Newtonsoft.Json.Utilities
         #region Write
         internal static void WriteDateTimeString(TextWriter writer, DateTime value, DateFormatHandling format, string? formatString, CultureInfo culture)
         {
-            if (string.IsNullOrEmpty(formatString))
+            if (StringUtils.IsNullOrEmpty(formatString))
             {
                 char[] chars = new char[64];
                 int pos = WriteDateTimeString(chars, 0, value, null, value.Kind, format);
@@ -753,7 +753,7 @@ namespace Newtonsoft.Json.Utilities
 #if HAVE_DATE_TIME_OFFSET
         internal static void WriteDateTimeOffsetString(TextWriter writer, DateTimeOffset value, DateFormatHandling format, string? formatString, CultureInfo culture)
         {
-            if (string.IsNullOrEmpty(formatString))
+            if (StringUtils.IsNullOrEmpty(formatString))
             {
                 char[] chars = new char[64];
                 int pos = WriteDateTimeString(chars, 0, (format == DateFormatHandling.IsoDateFormat) ? value.DateTime : value.UtcDateTime, value.Offset, DateTimeKind.Local, format);
diff --git a/Src/Newtonsoft.Json/Utilities/DictionaryWrapper.cs b/Src/Newtonsoft.Json/Utilities/DictionaryWrapper.cs
index 19a7a322..1d2ed07e 100644
--- a/Src/Newtonsoft.Json/Utilities/DictionaryWrapper.cs
+++ b/Src/Newtonsoft.Json/Utilities/DictionaryWrapper.cs
@@ -80,7 +80,7 @@ namespace Newtonsoft.Json.Utilities
         {
             get
             {
-                Debug.Assert(_genericDictionary != null);
+                MiscellaneousUtils.Assert(_genericDictionary != null);
                 return _genericDictionary;
             }
         }
diff --git a/Src/Newtonsoft.Json/Utilities/DynamicUtils.cs b/Src/Newtonsoft.Json/Utilities/DynamicUtils.cs
index 0daa1c1d..acb3e3a3 100644
--- a/Src/Newtonsoft.Json/Utilities/DynamicUtils.cs
+++ b/Src/Newtonsoft.Json/Utilities/DynamicUtils.cs
@@ -117,8 +117,8 @@ namespace Newtonsoft.Json.Utilities
             {
 #if !HAVE_REFLECTION_BINDER
                 Init();
-                Debug.Assert(_getMemberCall != null);
-                Debug.Assert(_getCSharpArgumentInfoArray != null);
+                MiscellaneousUtils.Assert(_getMemberCall != null);
+                MiscellaneousUtils.Assert(_getCSharpArgumentInfoArray != null);
                 return (CallSiteBinder)_getMemberCall(null, 0, name, context, _getCSharpArgumentInfoArray)!;
 #else
                 return Binder.GetMember(
@@ -130,8 +130,8 @@ namespace Newtonsoft.Json.Utilities
             {
 #if !HAVE_REFLECTION_BINDER
                 Init();
-                Debug.Assert(_setMemberCall != null);
-                Debug.Assert(_setCSharpArgumentInfoArray != null);
+                MiscellaneousUtils.Assert(_setMemberCall != null);
+                MiscellaneousUtils.Assert(_setCSharpArgumentInfoArray != null);
                 return (CallSiteBinder)_setMemberCall(null, 0, name, context, _setCSharpArgumentInfoArray)!;
 #else
                 return Binder.SetMember(
diff --git a/Src/Newtonsoft.Json/Utilities/FSharpUtils.cs b/Src/Newtonsoft.Json/Utilities/FSharpUtils.cs
index 718975b9..cb816660 100644
--- a/Src/Newtonsoft.Json/Utilities/FSharpUtils.cs
+++ b/Src/Newtonsoft.Json/Utilities/FSharpUtils.cs
@@ -94,7 +94,7 @@ namespace Newtonsoft.Json.Utilities
         {
             get
             {
-                Debug.Assert(_instance != null);
+                MiscellaneousUtils.Assert(_instance != null);
                 return _instance;
             }
         }
diff --git a/Src/Newtonsoft.Json/Utilities/JavaScriptUtils.cs b/Src/Newtonsoft.Json/Utilities/JavaScriptUtils.cs
index 80fb1b65..fbcacf97 100644
--- a/Src/Newtonsoft.Json/Utilities/JavaScriptUtils.cs
+++ b/Src/Newtonsoft.Json/Utilities/JavaScriptUtils.cs
@@ -153,7 +153,7 @@ namespace Newtonsoft.Json.Utilities
                 writer.Write(delimiter);
             }
 
-            if (!string.IsNullOrEmpty(s))
+            if (!StringUtils.IsNullOrEmpty(s))
             {
                 int lastWritePosition = FirstCharToEscape(s, charEscapeFlags, stringEscapeHandling);
                 if (lastWritePosition == -1)
@@ -266,7 +266,7 @@ namespace Newtonsoft.Json.Utilities
                                 // copy it over when creating new buffer
                                 if (isEscapedUnicodeText)
                                 {
-                                    Debug.Assert(writeBuffer != null, "Write buffer should never be null because it is set when the escaped unicode text is encountered.");
+                                    MiscellaneousUtils.Assert(writeBuffer != null, "Write buffer should never be null because it is set when the escaped unicode text is encountered.");
 
                                     Array.Copy(writeBuffer, newBuffer, UnicodeTextLength);
                                 }
@@ -293,7 +293,7 @@ namespace Newtonsoft.Json.Utilities
                         }
                     }
 
-                    Debug.Assert(lastWritePosition != 0);
+                    MiscellaneousUtils.Assert(lastWritePosition != 0);
                     length = s.Length - lastWritePosition;
                     if (length > 0)
                     {
@@ -374,7 +374,7 @@ namespace Newtonsoft.Json.Utilities
                 return WriteEscapedJavaScriptStringWithDelimitersAsync(writer, s, delimiter, charEscapeFlags, stringEscapeHandling, client, writeBuffer, cancellationToken);
             }
 
-            if (string.IsNullOrEmpty(s))
+            if (StringUtils.IsNullOrEmpty(s))
             {
                 return cancellationToken.CancelIfRequestedAsync() ?? AsyncUtils.CompletedTask;
             }
@@ -391,7 +391,7 @@ namespace Newtonsoft.Json.Utilities
                 return WriteEscapedJavaScriptStringWithDelimitersAsync(task, writer, s, delimiter, charEscapeFlags, stringEscapeHandling, client, writeBuffer, cancellationToken);
             }
 
-            if (!string.IsNullOrEmpty(s))
+            if (!StringUtils.IsNullOrEmpty(s))
             {
                 task = WriteEscapedJavaScriptStringWithoutDelimitersAsync(writer, s, charEscapeFlags, stringEscapeHandling, client, writeBuffer, cancellationToken);
                 if (task.IsCompletedSucessfully())
@@ -409,7 +409,7 @@ namespace Newtonsoft.Json.Utilities
         {
             await task.ConfigureAwait(false);
 
-            if (!string.IsNullOrEmpty(s))
+            if (!StringUtils.IsNullOrEmpty(s))
             {
                 await WriteEscapedJavaScriptStringWithoutDelimitersAsync(writer, s, charEscapeFlags, stringEscapeHandling, client, writeBuffer, cancellationToken).ConfigureAwait(false);
             }
diff --git a/Src/Newtonsoft.Json/Utilities/LinqBridge.cs b/Src/Newtonsoft.Json/Utilities/LinqBridge.cs
index fe93b82c..e1dba08a 100644
--- a/Src/Newtonsoft.Json/Utilities/LinqBridge.cs
+++ b/Src/Newtonsoft.Json/Utilities/LinqBridge.cs
@@ -377,7 +377,7 @@ namespace Newtonsoft.Json.Utilities.LinqBridge
       Func<TSource> empty)
     {
       CheckNotNull(source, "source");
-      Debug.Assert(empty != null);
+      MiscellaneousUtils.Assert(empty != null);
 
       var list = source as IList<TSource>; // optimized case for lists
       if (list != null)
@@ -1364,7 +1364,7 @@ namespace Newtonsoft.Json.Utilities.LinqBridge
       Func<TSource, TSource, bool> lesser)
     {
       CheckNotNull(source, "source");
-      Debug.Assert(lesser != null);
+      MiscellaneousUtils.Assert(lesser != null);
 
       return source.Aggregate((a, item) => lesser(a, item) ? a : item);
     }
@@ -1378,7 +1378,7 @@ namespace Newtonsoft.Json.Utilities.LinqBridge
       TSource? seed, Func<TSource?, TSource?, bool> lesser) where TSource : struct
     {
       CheckNotNull(source, "source");
-      Debug.Assert(lesser != null);
+      MiscellaneousUtils.Assert(lesser != null);
 
       return source.Aggregate(seed, (a, item) => lesser(a, item) ? a : item);
       //  == MinMaxImpl(Repeat<TSource?>(null, 1).Concat(source), lesser);
@@ -1442,7 +1442,7 @@ namespace Newtonsoft.Json.Utilities.LinqBridge
 
     private static IEnumerable<T> Renumerable<T>(this IEnumerator<T> e)
     {
-      Debug.Assert(e != null);
+      MiscellaneousUtils.Assert(e != null);
 
       do
       {
diff --git a/Src/Newtonsoft.Json/Utilities/MiscellaneousUtils.cs b/Src/Newtonsoft.Json/Utilities/MiscellaneousUtils.cs
index 70a1583b..137ec445 100644
--- a/Src/Newtonsoft.Json/Utilities/MiscellaneousUtils.cs
+++ b/Src/Newtonsoft.Json/Utilities/MiscellaneousUtils.cs
@@ -31,6 +31,8 @@ using System.Reflection;
 using System.Text;
 using System.Globalization;
 using System.Text.RegularExpressions;
+using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 
 namespace Newtonsoft.Json.Utilities
 {
@@ -38,6 +40,12 @@ namespace Newtonsoft.Json.Utilities
 
     internal static class MiscellaneousUtils
     {
+        [Conditional("DEBUG")]
+        public static void Assert([DoesNotReturnIf(false)] bool condition, string? message = null)
+        {
+            Debug.Assert(condition, message);
+        }
+
         public static bool ValueEquals(object? objA, object? objB)
         {
             if (objA == objB)
diff --git a/Src/Newtonsoft.Json/Utilities/NullableAttributes.cs b/Src/Newtonsoft.Json/Utilities/NullableAttributes.cs
index ce153f2c..fa1f55e9 100644
--- a/Src/Newtonsoft.Json/Utilities/NullableAttributes.cs
+++ b/Src/Newtonsoft.Json/Utilities/NullableAttributes.cs
@@ -52,4 +52,23 @@ namespace System.Diagnostics.CodeAnalysis
     [AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property, Inherited = false)]
     internal sealed class AllowNullAttribute : Attribute
     { }
+
+    /// <summary>
+    /// Specifies that the method will not return if the associated Boolean parameter is passed the specified value.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
+    internal class DoesNotReturnIfAttribute : Attribute
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DoesNotReturnIfAttribute"/> class.
+        /// </summary>
+        /// <param name="parameterValue">
+        /// The condition parameter value. Code after the method will be considered unreachable by diagnostics if the argument to
+        /// the associated parameter matches this value.
+        /// </param>
+        public DoesNotReturnIfAttribute(bool parameterValue) => this.ParameterValue = parameterValue;
+
+        /// <summary>Gets the condition parameter value.</summary>
+        public bool ParameterValue { get; }
+    }
 }
\ No newline at end of file
diff --git a/Src/Newtonsoft.Json/Utilities/StringUtils.cs b/Src/Newtonsoft.Json/Utilities/StringUtils.cs
index 8544a3f5..f07ffc4c 100644
--- a/Src/Newtonsoft.Json/Utilities/StringUtils.cs
+++ b/Src/Newtonsoft.Json/Utilities/StringUtils.cs
@@ -28,6 +28,7 @@ using System.Collections.Generic;
 using System.IO;
 using System.Text;
 using System.Globalization;
+using System.Diagnostics.CodeAnalysis;
 #if !HAVE_LINQ
 using Newtonsoft.Json.Utilities.LinqBridge;
 #else
@@ -45,6 +46,11 @@ namespace Newtonsoft.Json.Utilities
         public const char LineFeed = '\n';
         public const char Tab = '\t';
 
+        public static bool IsNullOrEmpty([NotNullWhen(false)] string? value)
+        {
+            return string.IsNullOrEmpty(value);
+        }
+
         public static string FormatWith(this string format, IFormatProvider provider, object? arg0)
         {
             return format.FormatWith(provider, new object?[] { arg0 });
@@ -148,7 +154,7 @@ namespace Newtonsoft.Json.Utilities
 
         public static string ToCamelCase(string s)
         {
-            if (string.IsNullOrEmpty(s) || !char.IsUpper(s[0]))
+            if (StringUtils.IsNullOrEmpty(s) || !char.IsUpper(s[0]))
             {
                 return s;
             }
@@ -207,7 +213,7 @@ namespace Newtonsoft.Json.Utilities
 
         public static string ToSnakeCase(string s)
         {
-            if (string.IsNullOrEmpty(s))
+            if (StringUtils.IsNullOrEmpty(s))
             {
                 return s;
             }