code: public function sendErrorResponse($message, $code, $httpStatusCode, $data = null)
      {
  
          \Yii::$app->response->format = Response::FORMAT_JSON;
          \Yii::$app->response->setStatusCode($httpStatusCode, $this->httpStatuses->getReasonPhrase($httpStatusCode));
  
          $response = [
              'status' => 'error',
              'message' => $message,
              'code' => $code
          ];
  
          if (!is_null($data)) {
              $response["data"] = $data;
          }
  
          return $response;
      }
docs: Allows sending error response
  @author Oluwarotimi Akintewe <akintewe.rotimi@gmail.com>
  @author Adegoke Obasa <goke@cottacush.com>
  @param $message
  @param $code
  @param $httpStatusCode
  @param null $data
  @return array