Show flash messages on saving settings

src/Controller/SettingsController.php

@@ -33,6 +33,8 @@ use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\Routing\Attribute\Route;
 use Symfony\Contracts\Cache\TagAwareCacheInterface;
 
+use function Symfony\Component\Translation\t;
+
 class SettingsController extends AbstractController
 {
     public function __construct(private readonly SettingsManagerInterface $settingsManager, private readonly SettingsFormFactoryInterface $settingsFormFactory)
@@ -63,6 +65,12 @@ class SettingsController extends AbstractController
 
             //It might be possible, that the tree settings have changed, so clear the cache
             $cache->invalidateTags(['tree_treeview', 'sidebar_tree_update']);
+
+            $this->addFlash('success', t('settings.flash.saved'));
+        }
+
+        if ($form->isSubmitted() && !$form->isValid()) {
+            $this->addFlash('error', t('settings.flash.invalid'));
         }
 
         //Render the form
@@ -70,4 +78,4 @@ class SettingsController extends AbstractController
             'form' => $form
         ]);
     }
-}
+}

translations/messages.en.xlf

@@ -13033,5 +13033,17 @@ Please note, that you can not impersonate a disabled user. If you try you will g
         <target>The value of this parameter can be overridden by setting the environment variable "%env%".</target>
       </segment>
     </unit>
+    <unit id="boWkQh7" name="settings.flash.saved">
+      <segment>
+        <source>settings.flash.saved</source>
+        <target>Settings saved successfully.</target>
+      </segment>
+    </unit>
+    <unit id="tEYWrWD" name="settings.flash.invalid">
+      <segment>
+        <source>settings.flash.invalid</source>
+        <target>Settings are invalid. Please check your input!</target>
+      </segment>
+    </unit>
   </file>
 </xliff>