-Fixed unhelpful error when failing conversion in JsonReader.ReadAsDecimal

-Fixed JsonReader.ReadAsInt32 with BigInteger values

Src/Newtonsoft.Json.Tests/JsonTextReaderTests/ReadAsyncTests.cs

@@ -67,6 +67,28 @@ namespace Newtonsoft.Json.Tests.JsonTextReaderTests
             );
         }
 
+        [Test]
+        public async Task ReadAsDecimalAsync_IntegerTooLarge_ThrowsJsonReaderException()
+        {
+            JValue token = new JValue(double.MaxValue);
+
+            await ExceptionAssert.ThrowsAsync<JsonReaderException>(
+                () => token.CreateReader().ReadAsDecimalAsync(),
+                "Could not convert to decimal: 1.79769313486232E+308. Path ''."
+            );
+        }
+
+#if !(NET20 || NET35 || PORTABLE40 || PORTABLE) || NETSTANDARD1_3 || NETSTANDARD2_0
+        [Test]
+        public async Task ReadAsInt32Async_BigIntegerValue_Success()
+        {
+            JValue token = new JValue(BigInteger.Parse("1"));
+
+            int? i = await token.CreateReader().ReadAsInt32Async();
+            Assert.AreEqual(1, i);
+        }
+#endif
+
         [Test]
         public async Task ReadMissingInt64()
         {

Src/Newtonsoft.Json.Tests/JsonTextReaderTests/ReadTests.cs

@@ -72,6 +72,28 @@ namespace Newtonsoft.Json.Tests.JsonTextReaderTests
             );
         }
 
+        [Test]
+        public void ReadAsDecimal_IntegerTooLarge_ThrowsJsonReaderException()
+        {
+            JValue token = new JValue(double.MaxValue);
+
+            ExceptionAssert.Throws<JsonReaderException>(
+                () => token.CreateReader().ReadAsDecimal(),
+                "Could not convert to decimal: 1.79769313486232E+308. Path ''."
+            );
+        }
+
+#if !(NET20 || NET35 || PORTABLE40 || PORTABLE) || NETSTANDARD1_3 || NETSTANDARD2_0
+        [Test]
+        public void ReadAsInt32_BigIntegerValue_Success()
+        {
+            JValue token = new JValue(BigInteger.Parse("1"));
+
+            int? i = token.CreateReader().ReadAsInt32();
+            Assert.AreEqual(1, i);
+        }
+#endif
+
         [Test]
         public void ReadMissingInt64()
         {

Src/Newtonsoft.Json/JsonReader.cs

@@ -414,14 +414,23 @@ namespace Newtonsoft.Json
                         return i;
                     }
 
-                    try
+#if HAVE_BIG_INTEGER
+                    if (v is BigInteger value)
                     {
-                        i = Convert.ToInt32(v, CultureInfo.InvariantCulture);
+                        i = (int)value;
                     }
-                    catch (Exception ex)
+                    else
+#endif
                     {
-                        // handle error for large integer overflow exceptions
-                        throw JsonReaderException.Create(this, "Could not convert to integer: {0}.".FormatWith(CultureInfo.InvariantCulture, v), ex);
+                        try
+                        {
+                            i = Convert.ToInt32(v, CultureInfo.InvariantCulture);
+                        }
+                        catch (Exception ex)
+                        {
+                            // handle error for large integer overflow exceptions
+                            throw JsonReaderException.Create(this, "Could not convert to integer: {0}.".FormatWith(CultureInfo.InvariantCulture, v), ex);
+                        }
                     }
 
                     SetToken(JsonToken.Integer, i, false);
@@ -756,7 +765,15 @@ namespace Newtonsoft.Json
                     else
 #endif
                     {
-                        d = Convert.ToDecimal(v, CultureInfo.InvariantCulture);
+                        try
+                        {
+                            d = Convert.ToDecimal(v, CultureInfo.InvariantCulture);
+                        }
+                        catch (Exception ex)
+                        {
+                            // handle error for large integer overflow exceptions
+                            throw JsonReaderException.Create(this, "Could not convert to decimal: {0}.".FormatWith(CultureInfo.InvariantCulture, v), ex);
+                        }
                     }
 
                     SetToken(JsonToken.Float, d, false);