- Проверяем зависимоти

common/modules/school/assets/WidgetAssetBundle.php

@@ -25,6 +25,7 @@ class WidgetAssetBundle extends AssetBundle
 	];
     public $depends = [
         'yii\web\YiiAsset',
+        'yii\web\JqueryAsset',
         'yii\bootstrap\BootstrapAsset',
     ];
 }

frontend/assets/AppAsset.php

@@ -40,6 +40,7 @@ class AppAsset extends AssetBundle
     ];
     public $depends = [
         'yii\web\YiiAsset',
+        'yii\web\JqueryAsset',
         'yii\bootstrap\BootstrapAsset',
         'common\assets\JqueryCookieAsset',
     ];