title: Flutter Google Maps app throws exception and crashes in browser , but not on Android
body: <p>I am using <a href="https://github.com/whatsupcoders/Flutter-GoogleMaps" rel="nofollow noreferrer">this code</a>, which accompanies <a href="https://www.youtube.com/watch?v=lNqEfnnmoHk" rel="nofollow noreferrer">this</a> popular YouTube tutorial. It is part of a  large series, with lots of views, so I would expect it to be good code. Also, it runs just fine on Android.</p>
  
  <p>I followed the official <a href="https://flutter.dev/docs/get-started/web" rel="nofollow noreferrer">Building a web application with Flutter</a>, but, when I launch my app in the browser, it crashes.</p>
  
  <p>Here's the trace before the crash:</p>
  
  <blockquote>
    <p>dart.developer.registerExtension ext.flutter.inspector.getChildren
    developer_patch.dart:65:72 dart.developer.registerExtension
    ext.flutter.inspector.getChildrenSummaryTree
    developer_patch.dart:65:72 dart.developer.registerExtension
    ext.flutter.inspector.getChildrenDetailsSubtree
    developer_patch.dart:65:72 dart.developer.registerExtension
    ext.flutter.inspector.getRootWidget developer_patch.dart:65:72
    dart.developer.registerExtension
    ext.flutter.inspector.getRootRenderObject developer_patch.dart:65:72
    dart.developer.registerExtension
    ext.flutter.inspector.getRootWidgetSummaryTree
    developer_patch.dart:65:72 dart.developer.registerExtension
    ext.flutter.inspector.getDetailsSubtree developer_patch.dart:65:72
    dart.developer.registerExtension
    ext.flutter.inspector.getSelectedRenderObject
    developer_patch.dart:65:72 dart.developer.registerExtension
    ext.flutter.inspector.getSelectedWidget developer_patch.dart:65:72
    dart.developer.registerExtension
    ext.flutter.inspector.getSelectedSummaryWidget
    developer_patch.dart:65:72 dart.developer.registerExtension
    ext.flutter.inspector.isWidgetCreationTracked
    developer_patch.dart:65:72 dart.developer.registerExtension
    ext.flutter.inspector.screenshot developer_patch.dart:65:72
    dart.developer.postEvent Flutter.FrameworkInitialization {}
    developer_patch.dart:98:16</p>
  </blockquote>
  
  <p>It crashes at the call to <code>super()</code> in the following code (dart_sdk.js, line 6327)</p>
  
  <pre><code>  dart.DartError = class DartError extends Error {
      constructor(error) {
        super();
        if (error == null) error = new core.NullThrownError.new();
        this[dart._thrownValue] = error;
        if (error != null &amp;&amp; typeof error == "object" &amp;&amp; error[dart._jsError] == null) {
          error[dart._jsError] = this;
        }
      }
      get message() {
        return dart.toString(this[dart._thrownValue]);
      }
    };
  </code></pre>
  
  <p>here's the call stack</p>
  
  <blockquote>
    <p>console.trace() debugger eval code:1:9<br>
         debugger eval code:1<br>
        DartError dart_sdk.js:6327<br>
        throw_ errors.dart:216<br>
        decodeEnvelope message_codecs.dart:569<br>
        _invokeMethod platform_channel.dart:156<br>
        onValue async_patch.dart:47<br>
        runUnary zone.dart:1439<br>
        handleValue future_impl.dart:141<br>
        handleValueCallback future_impl.dart:686<br>
        _propagateToListeners future_impl.dart:715<br>
        _completeWithValue future_impl.dart:526<br>
         future_impl.dart:560<br>
        _microtaskLoop schedule_microtask.dart:43<br>
        _startMicrotaskLoop schedule_microtask.dart:52<br>
        _scheduleImmediateWithPromise async_patch.dart:168  </p>
  </blockquote>
  
  <p>Question: is there anything I can do about this? I don't see any reference to "my" code (since its asynch), nor any way to find if it is a problem in "my code". It runs just fine on Android.</p>
  
  <p>[Update] I also tried it with the simplest possible static map, albeit iwht a single marker, and got the same result.</p>
  
  <p>Do I have to accept that Flutter for the web is on the Beta Channel and leave it a few months to see if it stabilizes? Or, does someone have a browser based Flutter Google Maps demo?</p>