public function error()
 {
     $error = parent::error();
     if ($error) {
         return $error;
     }
     if (!is_array($this->data)) {
         return sprintf('transloadit: bad response, no json: %s', $this->data);
     }
     if (array_key_exists('error', $this->data)) {
         $error = sprintf('transloadit: %s', $this->data['error']);
         if (array_key_exists('message', $this->data)) {
             $error .= sprintf(': %s', $this->data['message']);
         }
         if (array_key_exists('reason', $this->data)) {
             $error .= sprintf(': %s', $this->data['reason']);
         }
         return $error;
     }
     if (!array_key_exists('ok', $this->data)) {
         return 'transloadit: bad response data, no ok / error key included.';
     }
     return false;
 }