Exception thrown in flutter_example/lib/openid_browser.dart

[hubertvolz]

Unfortunately the throw Exception('Will never reach here'); is executed:

Future<Credential> authenticate(Client client,
    {List<String> scopes = const []}) async {
  var authenticator = browser.Authenticator(client, scopes: scopes);

  authenticator.authorize();

  throw Exception('Will never reach here');
}

output:

The Flutter DevTools debugger and profiler on Chrome is available at: http://127.0.0.1:9105?uri=http://127.0.0.1:50809/w5nk5QXjN2k=

Error: Exception: Will never reach here

    at Object.throw_ [as throw] (http://localhost:50669/dart_sdk.js:5241:11)
    at authenticate (http://localhost:50669/packages/example/openid_browser.dart.lib.js:38:17)
    at authenticate.next (<anonymous>)
    at runBody (http://localhost:50669/dart_sdk.js:40595:34)
    at Object._async [as async] (http://localhost:50669/dart_sdk.js:40626:7)
    at Object.authenticate (http://localhost:50669/packages/example/openid_browser.dart.lib.js:26:18)
    at main._MyHomePageState.new.<anonymous> (http://localhost:50669/packages/example/main.dart.lib.js:466:58)
    at Generator.next (<anonymous>)
    at runBody (http://localhost:50669/dart_sdk.js:40595:34)
    at Object._async [as async] (http://localhost:50669/dart_sdk.js:40626:7)
    at http://localhost:50669/packages/example/main.dart.lib.js:464:145
    at ink_well._InkResponseState.new.handleTap (http://localhost:50669/packages/flutter/src/material/icon_button.dart.lib.js:42992:31)
    at tap.TapGestureRecognizer.new.invokeCallback (http://localhost:50669/packages/flutter/src/gestures/recognizer.dart.lib.js:214:18)
    at tap.TapGestureRecognizer.new.handleTapUp (http://localhost:50669/packages/flutter/src/gestures/tap.dart.lib.js:429:20)
    at [_checkUp] (http://localhost:50669/packages/flutter/src/gestures/tap.dart.lib.js:220:12)
    at tap.TapGestureRecognizer.new.handlePrimaryPointer (http://localhost:50669/packages/flutter/src/gestures/tap.dart.lib.js:167:23)
    at tap.TapGestureRecognizer.new.handleEvent (http://localhost:50669/packages/flutter/src/gestures/recognizer.dart.lib.js:474:16)
    at [_dispatch] (http://localhost:50669/packages/flutter/src/gestures/pointer_router.dart.lib.js:89:9)
    at http://localhost:50669/packages/flutter/src/gestures/pointer_router.dart.lib.js:115:26
    at LinkedMap.new.forEach (http://localhost:50669/dart_sdk.js:27933:11)
    at [_dispatchEventToRoutes] (http://localhost:50669/packages/flutter/src/gestures/pointer_router.dart.lib.js:113:29)
    at pointer_router.PointerRouter.new.route (http://localhost:50669/packages/flutter/src/gestures/pointer_router.dart.lib.js:108:37)
    at binding$5.WidgetsFlutterBinding.new.handleEvent (http://localhost:50669/packages/flutter/src/gestures/binding.dart.lib.js:377:26)
    at binding$5.WidgetsFlutterBinding.new.dispatchEvent (http://localhost:50669/packages/flutter/src/gestures/binding.dart.lib.js:365:24)
    at binding$5.WidgetsFlutterBinding.new.dispatchEvent (http://localhost:50669/packages/flutter/src/rendering/view.dart.lib.js:680:13)
    at [_handlePointerEventImmediately] (http://localhost:50669/packages/flutter/src/gestures/binding.dart.lib.js:341:14)
    at binding$5.WidgetsFlutterBinding.new.handlePointerEvent
    (http://localhost:50669/packages/flutter/src/gestures/binding.dart.lib.js:311:43)
    at [_flushPointerEventQueue] (http://localhost:50669/packages/flutter/src/gestures/binding.dart.lib.js:300:14)
    at [_handlePointerDataPacket] (http://localhost:50669/packages/flutter/src/gestures/binding.dart.lib.js:288:38)
    at Object.invoke1 (http://localhost:50669/dart_sdk.js:196999:7)
    at _engine.EnginePlatformDispatcher.new.invokeOnPointerDataPacket (http://localhost:50669/dart_sdk.js:172339:15)
    at [_onPointerData] (http://localhost:50669/dart_sdk.js:173317:49)
    at http://localhost:50669/dart_sdk.js:173842:30
    at http://localhost:50669/dart_sdk.js:173785:9
    at loggedHandler (http://localhost:50669/dart_sdk.js:173490:11)
    at http://localhost:50669/dart_sdk.js:173408:91
    at Object._checkAndCall (http://localhost:50669/dart_sdk.js:5438:16)
    at Object.dcall (http://localhost:50669/dart_sdk.js:5443:17)
    at ret (http://localhost:50669/dart_sdk.js:62137:21)
Flutter Web Bootstrap: Programmatic

Steps to reproduce:

• start keycloak as mentioned in example.md
• flutter run -d chrome
• press login button

The error happens after pressing the Login button in chrome and before Login Screen of keycloak is shown.

Everything works fine if I run flutter run -d macos.

[rbellens]

Ok, that's unfortunate indeed, but if I understand correctly, you are still redirected to the login screen and you are still able to login?

I should probably replace that line with a never completing Future.

[hubertvolz]

Yes, I got redirected and I'm able to login, so your code works perfectly. Only the exception was misleading me.

[gitvadim]

Faced the same issue, however got it fixed by changing the method a bit into:

void authenticate(Client client, {List<String> scopes = const []}) {
  var authenticator = browser.Authenticator(client, scopes: scopes);
  authenticator.authorize();
}

Can someone please explain to me why the original method in the example is async to begin with and its signature says it's returning a Future<Credential> if it's not returning anything?

[LinetCheese]

It seems just making the authenticate() function call the authorize() like @gitvadim wrote above is enough - just need to reduce the Login button callback to it:

// ...
OutlinedButton(
    child: const Text('Login'),
    onPressed: () {
      authenticate(client, scopes: scopes);
    }),
// ...

Still feels awkward for a solution though...

Edit: removed forgotten async from the callback.

[rbellens]

should be fixed in version 0.4.8