code: protected function parseErrorMessage($messageKey, $params = [])
      {
          $messages = $this->getErrorMessages();
          if (isset($messages[$messageKey])) {
              $message = $messages[$messageKey];
          } else {
              $message = Yii::t('yii', 'The format of {filter} is invalid.');
          }
  
          $params = array_merge(
              [
                  'filter' => $this->getAttributeLabel($this->filterAttributeName),
              ],
              $params
          );
  
          return Yii::$app->getI18n()->format($message, $params, Yii::$app->language);
      }
docs: Parses content of the message from [[errorMessages]], specified by message key.
  @param string $messageKey message key.
  @param array $params params to be parsed into the message.
  @return string composed message string.