Specify MDJsonEncodingFailedException for failure to encode JSON through

MD_STD::json_encode

src/MD_STD.php

@@ -242,7 +242,7 @@ public static function json_encode(array $value, int $options = 0, int $depth =
 
         $output = \json_encode($value, $options, $depth);
         if ($output === false) {
-            throw new Exception("JSON output could not be generated");
+            throw new MDJsonEncodingFailedException("JSON output could not be generated");
         }
         return $output;
 
@@ -263,7 +263,7 @@ public static function json_encode_object(object $value, int $options = 0, int $
 
         $output = \json_encode($value, $options, $depth);
         if ($output === false) {
-            throw new Exception("JSON output could not be generated");
+            throw new MDJsonEncodingFailedException("JSON output could not be generated");
         }
         return $output;