code: public function init()
      {
          parent::init();
          if ($this->enableIDN && !function_exists('idn_to_ascii')) {
              throw new InvalidConfigException('In order to use IDN validation intl extension must be installed and enabled.');
          }
          if ($this->message === null) {
              $this->message = Yii::t('yii', '{attribute} is not a valid URL.');
          }
      }
docs: {@inheritdoc}