code: protected function defaultErrorMessages()
      {
          return [
              'invalidFilter' => Yii::t('yii', 'The format of {filter} is invalid.'),
              'operatorRequireMultipleOperands' => Yii::t('yii', 'Operator "{operator}" requires multiple operands.'),
              'unknownAttribute' => Yii::t('yii', 'Unknown filter attribute "{attribute}"'),
              'invalidAttributeValueFormat' => Yii::t('yii', 'Condition for "{attribute}" should be either a value or valid operator specification.'),
              'operatorRequireAttribute' => Yii::t('yii', 'Operator "{operator}" must be used with a search attribute.'),
              'unsupportedOperatorType' => Yii::t('yii', '"{attribute}" does not support operator "{operator}".'),
          ];
      }
docs: Returns default values for [[errorMessages]].
  @return array default error messages in `[errorKey => message]` format.