Added check for invalid responses which are not empty.

Author: Benjamin

src/Parse/ParseClient.php

@@ -493,6 +493,12 @@ public static function _request(
         }
 
         $decoded = json_decode($response, true);
+
+        if(!isset($decoded) && $response !== '') {
+            throw new ParseException('Bad Request. Could not decode Response', -1);
+
+        }
+
         if (isset($decoded['error'])) {
             // check to convert error to a string, if an array
             // used to handle an Array 'error' from back4app.com