kartik\builder\FormTrait::checkBaseConfig PHP Method

    protected function checkBaseConfig()
    {
        if (empty($this->form) && empty($this->formName)) {
            throw new InvalidConfigException("The 'formName' property must be set when you are not using with ActiveForm.");
        }
        if (!empty($this->form) && !$this->form instanceof ActiveForm) {
            throw new InvalidConfigException("The 'form' property must be an instance of '\\kartik\\widgets\\ActiveForm' or '\\kartik\\form\\ActiveForm'.");
        }
        if (empty($this->attributes)) {
            throw new InvalidConfigException("The 'attributes' array must be set.");
        }
    }