Frontend first draft

frontend/pweb/lib/utils/notify.dart

@@ -0,0 +1,38 @@
+import 'package:flutter/material.dart';
+
+import 'package:pweb/generated/i18n/app_localizations.dart';
+import 'package:pweb/utils/snackbar.dart';
+import 'package:pweb/widgets/error/snackbar.dart';
+
+
+Future<void> invokeAndNotify<T>(
+  BuildContext context, {
+  required Future<T> Function() operation,
+  String? operationSuccess,
+  String? operationError,
+  void Function(Object)? onError,
+  void Function(T)? onSuccess,
+}) async {
+  final sm = ScaffoldMessenger.of(context);
+  final locs = AppLocalizations.of(context)!;
+  try {
+    final res = await operation();
+    if (operationSuccess != null) {
+      notifyUserX(sm, operationSuccess);
+    }
+    if (onSuccess != null) {
+      onSuccess(res);
+    }
+  } catch (e) {
+    notifyUserOfErrorX(
+      scaffoldMessenger: sm, 
+      errorSituation: operationError ?? locs.errorInternalError, 
+      exception: e, 
+      appLocalizations: locs,
+    );
+    if (onError != null) {
+      onError(e);
+    }
+    rethrow;
+  }
+}