Fatal error: Uncaught Error: Class 'yii\bootstrap\Alert' not found in /home/wittyly/public_html/staging/hr-witty/vendor/kartik-v/yii2-widget-alert/src/Bs3Alert.php:21 Stack trace: #0 {main} thrown in /home/wittyly/public_html/staging/hr-witty/vendor/kartik-v/yii2-widget-alert/src/Bs3Alert.php on line 21