Some updates

Signed-off-by: Nikolai Rodionov <nrodionov@eos-uptrade.de>

lib/main.dart

@@ -1,5 +1,4 @@
-import 'dart:html';
-
+import 'package:web/web.dart' as web;
 import 'package:flutter_dotenv/flutter_dotenv.dart';
 import 'package:flutter/material.dart';
 import 'package:grpc/grpc_web.dart';
@@ -51,7 +50,7 @@ class _StateRootWidget extends State<RootWidget> {
   }
 
   bool isSignedIn() {
-    return window.localStorage.containsKey("token");
+    return web.window.localStorage.getItem("token") != null;
   }
 
   final GlobalKey<ScaffoldState> _key = GlobalKey(); // Create a key