* Initialize the variable.

module/story/control.php

@@ -1947,6 +1947,7 @@ class story extends control
     {
         $this->loadModel('report');
         $this->view->charts = array();
+        $this->view->datas  = array();
 
         if(!empty($_POST))
         {

module/story/ui/report.html.php

@@ -38,7 +38,7 @@ $fnGenerateTabCharts = function(string $type) use($charts, $lang, $datas)
         (
             set::type($type),
             set::title($lang->story->report->charts[$chartType]),
-            set::datas($datas[$chartType]),
+            set::datas($datas[$chartType] ?? null),
             set::tableHeaders(array
             (
                 'item'    => $lang->story->report->$chartType->item,