app\components\Helper::checkPagesSetup PHP Method

    private static function checkPagesSetup()
    {
        if (!\Yii::$app->getModule('pages')->getLocalizedRootNode()) {
            $link = Html::a('pages module', ['/pages']);
            \Yii::$app->session->addFlash('warning', "There is no navigation root node, visit {$link} to create a root node.");
        }
    }