Fatal error: Uncaught Error: Class "yii\base\Behavior" not found in /home/telefonai/public_html/test.telefonai.eu/vendor/creocoder/yii2-nested-sets/src/NestedSetsBehavior.php:23 Stack trace: #0 {main} thrown in /home/telefonai/public_html/test.telefonai.eu/vendor/creocoder/yii2-nested-sets/src/NestedSetsBehavior.php on line 23