Fix 3848: Error page does not use theme

protected/humhub/controllers/ErrorController.php

@@ -28,6 +28,9 @@ class ErrorController extends Controller
      */
     public function actionIndex()
     {
+        // Fix: https://github.com/humhub/humhub/issues/3848
+        Yii::$app->view->theme->register();
+
         if (($exception = Yii::$app->getErrorHandler()->exception) === null) {
             return '';
         }

protected/humhub/docs/CHANGELOG_DEV.md

@@ -40,6 +40,7 @@ HumHub Change Log (DEVELOP)
 - Fix: Settings cli rewrite dynamic config when required
 - Fix #3806: Using `Receive notifications for new content` will not include the space to the notification setting view until settings are saved
 - Enh: Added possibility to disable mail summary feature
+- Fix 3848: Error page does not use theme
 
 
 1.4.0-beta.2