Fixed parseValue of StringType and IDType: (it should return null on invalid value, not throw)

src/Type/Definition/IDType.php

@@ -55,9 +55,6 @@ When expected as an input type, any string (such as `"4"`) or integer
      */
     public function parseValue($value)
     {
-        if (!is_scalar($value)) {
-            throw new Error("ID type cannot represent non scalar value: " . Utils::printSafeJson($value));
-        }
         return (is_string($value) || is_int($value)) ? (string) $value : null;
     }
 

src/Type/Definition/StringType.php

@@ -52,9 +52,6 @@ represent free-form human-readable text.';
      */
     public function parseValue($value)
     {
-        if (!is_scalar($value)) {
-            throw new Error("String cannot represent non scalar value: " . Utils::printSafe($value));
-        }
         return is_string($value) ? $value : null;
     }