Change return type from `String` to `Jwt`

lib/hooks/logged_in_action.dart

@@ -0,0 +1,30 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_hooks/flutter_hooks.dart';
+import 'package:lemmy_api_client/lemmy_api_client.dart';
+
+import '../pages/settings.dart';
+import '../util/goto.dart';
+import 'stores.dart';
+
+Function(Function(Jwt token) action) useLoggedInAction(
+  String instanceUrl, [
+  String message,
+]) {
+  final context = useContext();
+  final store = useAccountsStore();
+
+  return (Function(Jwt token) action) {
+    if (store.isAnonymousFor(instanceUrl)) {
+      return () {
+        Scaffold.of(context).showSnackBar(SnackBar(
+          content: Text(message ?? 'you gotta be logged in to do that'),
+          action: SnackBarAction(
+              label: 'log in',
+              onPressed: () => goTo(context, (_) => AccountsConfigPage())),
+        ));
+      };
+    }
+    final token = store.defaultTokenFor(instanceUrl);
+    return () => action(token);
+  };
+}