Flutter can't load model-viewer

Question

I have a problem loadng a model-viewer Screen. It shouldn't be trivial. This is my main.dart , and I try to load InfoPage();

import 'package:flutter/material.dart';
import 'package:test/screens/info_page.dart';
import 'package:test/screens/monument_list.dart';
import 'package:test/screens/home_page.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'OpenWorld',
      theme: ThemeData(
      
        primarySwatch: Colors.deepPurple,
      ),
      initialRoute: '/',
      routes: {
        // When navigating to the "/" route, build the FirstScreen widget.
        '/': (context) => const MyHomePage(title: 'Home',),
        // When navigating to the "/second" route, build the SecondScreen widget.
        '/list': (context) => const MonumentList(),
        '/viewer': (context) => const InfoPage(title: 'Viewer'),
      },
      
    );
  }
}

It should load after pressing this tile

But whenever I pess it and it takes me to '/viewer' VS code pops this part of focus_manager.dart

That's the infoPage:

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

// ignore: import_of_legacy_library_into_null_safe
import 'package:model_viewer/model_viewer.dart';
import 'package:test/widgets/my_drawer.dart';

class InfoPage extends StatelessWidget {
  const InfoPage({Key? key, required this.title}) : super(key: key);
  // ignore: prefer_typing_uninitialized_variables
  final title;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(title: const Text("Model Viewer")),
        body: ModelViewer(
          src: 'assets/models/Astronaut.glb',
          alt: "A 3D model of an astronaut",
          ar: true,
          autoRotate: true,
          cameraControls: true,
        ),
      drawer: MyDrawer(title: title),
      
    );
  
  }
  
}

I have the installed all the packages and dependencies as flutter instructs. The Debug Console shows nothing... Please help me!

This is new! UPDATE 8th December 2021 I get this error:

    C:/b/s/w/ir/cache/builder/src/out/host_debug/flutter_web_sdk/lib/_engine/engine/platform_dispatcher.dart 1003:13           invoke
C:/b/s/w/ir/cache/builder/src/out/host_debug/flutter_web_sdk/lib/_engine/engine/platform_dispatcher.dart 157:5             invokeOnDrawFrame
C:/b/s/w/ir/cache/builder/src/out/host_debug/flutter_web_sdk/lib/_engine/engine.dart 440:45<fn>



The following UnsupportedError was thrown building WebView(dirty, state:
_WebViewState#92ba1):
Unsupported operation: Trying to use the default webview implementation for
TargetPlatform.windows
but there isn't a default one

The relevant error-causing widget was:
  WebView
  WebView:file:///C:/Users/PCcosmos/OneDrive/Documents/flutter/.pub-cache/hosted/pub.dartla  ng.org/model_viewer-0.8.1/lib/src/model_viewer.dart:121:12
When the exception was thrown, this was the stack:
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 251:49  throw_
packages/webview_flutter/webview_flutter.dart 189:11
get platform
packages/webview_flutter/webview_flutter.dart 344:29
buil

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