prevent existing bangs from getting overridden

app/lib/features/bangs/domain/repositories/data.dart

@@ -142,6 +142,14 @@ class BangDataRepository extends _$BangDataRepository {
         .deleteWhere((t) => t.trigger.equals(trigger));
   }
 
+  Future<BangData?> getBang(BangKey key) {
+    return ref
+        .read(bangDatabaseProvider)
+        .bangDao
+        .getBangData(key.group, key.trigger)
+        .getSingleOrNull();
+  }
+
   Future<void> upsertBang(Bang bang) {
     return ref.read(bangDatabaseProvider).bangDao.upsertBang(bang);
   }

app/lib/features/bangs/domain/repositories/data.g.dart

@@ -42,7 +42,7 @@ final class BangDataRepositoryProvider
 }
 
 String _$bangDataRepositoryHash() =>
-    r'f071d3c4ab8218d52d55acb3de8e01fd7a204e4d';
+    r'e3833d71ca51bfe51feb9f137e154dfebf8b053d';
 
 abstract class _$BangDataRepository extends $Notifier<void> {
   void build();

app/lib/features/bangs/presentation/screens/edit.dart

@@ -10,6 +10,7 @@ import 'package:weblibre/features/bangs/data/models/bang_key.dart';
 import 'package:weblibre/features/bangs/domain/providers/bangs.dart';
 import 'package:weblibre/features/bangs/domain/repositories/data.dart';
 import 'package:weblibre/utils/form_validators.dart';
+import 'package:weblibre/utils/ui_helper.dart' as ui_helper;
 
 class EditBangScreen extends HookConsumerWidget {
   final Bang? initialBang;
@@ -44,6 +45,29 @@ class EditBangScreen extends HookConsumerWidget {
           IconButton(
             onPressed: () async {
               if (formKey.currentState?.validate() ?? false) {
+                final existingBang = await ref
+                    .read(bangDataRepositoryProvider.notifier)
+                    .getBang(
+                      BangKey(
+                        group: BangGroup.user,
+                        trigger: triggerTextController.text,
+                      ),
+                    );
+
+                if ((initialBang == null && existingBang != null) ||
+                    (initialBang != null &&
+                        existingBang != null &&
+                        existingBang.trigger != initialBang!.trigger)) {
+                  if (context.mounted) {
+                    ui_helper.showErrorMessage(
+                      context,
+                      'A Bang with Trigger "${triggerTextController.text}" does already exist',
+                    );
+                  }
+
+                  return;
+                }
+
                 final uri = Uri.parse(urlTextController.text);
 
                 final bang = Bang(