Fatal error: Uncaught Error: Class 'yii\base\Behavior' not found in /home/mpolsk5/public_html/visibilityfuel.com/vendor/creocoder/yii2-nested-sets/src/NestedSetsBehavior.php:23 Stack trace: #0 {main} thrown in /home/mpolsk5/public_html/visibilityfuel.com/vendor/creocoder/yii2-nested-sets/src/NestedSetsBehavior.php on line 23