controllers/UserController.php
protected function _checkConfig()
    {
        if (!$this->query)
            throw new InvalidConfigException(Yii::t('wavecms/main', 'The "query" property must be set.'));

        if (!$this->query instanceof ActiveQuery)
            throw new InvalidConfigException(Yii::t('wavecms/main', 'The "query" property is not instance of ActiveQuery.'));
    }
protected function _checkConfig()
    {
        if (!$this->query)
            throw new InvalidConfigException(Yii::t('wavecms/main', 'The "query" property must be set.'));

        if (!$this->query instanceof ActiveQuery)
            throw new InvalidConfigException(Yii::t('wavecms/main', 'The "query" property is not instance of ActiveQuery.'));
    }
Check if $this->query is set
@throws \yii\base\InvalidConfigException