Repository: flutter
Issue: Attempted to send a key down event when no keys are in keysPressed, when using barcode scanner
Labels: a: text input,platform-windows,a: desktop,a: error message,P3,team-design,triaged-design

When I scan a barcode with my barcode scanner I get this error.

```
======== Exception caught by services library ======================================================
The following assertion was thrown during a platform message callback:
Attempted to send a key down event when no keys are in keysPressed. This state can occur if the key event being sent doesn't properly set its modifier flags. This was the event: RawKeyDownEvent#22ace(logicalKey: LogicalKeyboardKey#df100(keyId: "0x200000102", keyLabel: "Shift Left", debugName: "Shift Left"), physicalKey: PhysicalKeyboardKey#ed430(usbHidUsage: "0x000700e1", debugName: "Shift Left"), repeat: false) and its data: RawKeyEventDataWindows#b7606(keyCode: 160, scanCode: 42, characterCodePoint: 0, modifiers: 0)
'package:flutter/src/services/raw_keyboard.dart':
Failed assertion: line 695 pos 7: 'event is! RawKeyDownEvent || _keysPressed.isNotEmpty'


Either the assertion indicates an error in the framework itself, or we should provide substantially more information in this error message to help you determine and fix the underlying cause.
In either case, please report this assertion by filing a bug on GitHub:
  https://github.com/flutter/flutter/issues/new?template=2_bug.yml

When the exception was thrown, this was the stack: 
#2      RawKeyboard.handleRawKeyEvent (package:flutter/src/services/raw_keyboard.dart:695:7)
#3      KeyEventManager.handleRawKeyMessage (package:flutter/src/services/hardware_keyboard.dart:1050:30)
#4      BasicMessageChannel.setMessageHandler.<anonymous closure> (package:flutter/src/services/platform_channel.dart:223:49)
#5      _DefaultBinaryMessenger.setMessageHandler.<anonymous closure> (package:flutter/src/services/binding.dart:567:35)
#6      _invoke2 (dart:ui/hooks.dart:344:13)
#7      _ChannelCallbackRecord.invoke (dart:ui/channel_buffers.dart:45:5)
#8      _Channel.push (dart:ui/channel_buffers.dart:135:31)
#9      ChannelBuffers.push (dart:ui/channel_buffers.dart:343:17)
#10     PlatformDispatcher._dispatchPlatformMessage (dart:ui/platform_dispatcher.dart:722:22)
#11     _dispatchPlatformMessage (dart:ui/hooks.dart:257:31)
(elided 2 frames from class _AssertionError)
====================================================================================================
```

Platform: Windows

Keyboard: Azerty

Create new flutter project, and paste the "code" contents below in your main file.
While the app has focus, whenever you type on your keyboard, you should see the key events being printed in
the terminal.
To reproduce the error above, you'll need to use a barcode scanner, set it to Azerty keyboard layout, and scan a barcode with it.
The error happens on windows when using Azerty keyboard layout.
I don't know if it's something that happens with other keyboard layouts.

Main Code:

```
import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return Focus(
      onKeyEvent: (node, event) {
        print(event);
        return KeyEventResult.handled;
      },
      child: MaterialApp(
        title: 'Flutter Demo',
        theme: ThemeData(
          // This is the theme of your application.
          //
          // TRY THIS: Try running your application with "flutter run". You'll see
          // the application has a purple toolbar. Then, without quitting the app,
          // try changing the seedColor in the colorScheme below to Colors.green
          // and then invoke "hot reload" (save your changes or press the "hot
          // reload" button in a Flutter-supported IDE, or press "r" if you used
          // the command line to start the app).
          //
          // Notice that the counter didn't reset back to zero; the application
          // state is not lost during the reload. To reset the state, use hot
          // restart instead.
          //
          // This works for code too, not just values: Most code changes can be
          // tested with just a hot reload.
          colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
          useMaterial3: true,
        ),
        home: const MyHomePage(title: 'Flutter Demo Home Page'),
      ),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
        // TRY THIS: Try changing the color here to a specific color (to
        // Colors.amber, perhaps?) and trigger a hot reload to see the AppBar
        // change color while the other colors stay the same.
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
      body: Center(
        // Center is a layout widget. It takes a single child and positions it
        // in the middle of the parent.
        child: Column(
          // Column is also a layout widget. It takes a list of children and
          // arranges them vertically. By default, it sizes itself to fit its
          // children horizontally, and tries to be as tall as its parent.
          //
          // Column has various properties to control how it sizes itself and
          // how it positions its children. Here we use mainAxisAlignment to
          // center the children vertically; the main axis here is the vertical
          // axis because Columns are vertical (the cross axis would be
          // horizontal).
          //
          // TRY THIS: Invoke "debug painting" (choose the "Toggle Debug Paint"
          // action in the IDE, or press "p" in the console), to see the
          // wireframe for each widget.
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headlineMedium,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

```

Doctor:

```
[√] Flutter (Channel stable, 3.16.9, on Microsoft Windows [Version 10.0.19045.3930], locale nl-BE)
    • Flutter version 3.16.9 on channel stable at C:\flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 41456452f2 (3 weeks ago), 2024-01-25 10:06:23 -0800
    • Engine revision f40e976bed
    • Dart version 3.2.6
    • DevTools version 2.28.5

[√] Windows Version (Installed version of Windows is version 10 or higher)

[√] Android toolchain - develop for Android devices (Android SDK version 32.1.0-rc1)
    • Android SDK at C:\Users\PC-3030\AppData\Local\Android\sdk
    • Platform android-32, build-tools 32.1.0-rc1
    • Java binary at: C:\Program Files\Android\Android Studio\jbr\bin\java
    • Java version OpenJDK Runtime Environment (build 11.0.15+0-b2043.56-8887301)
    • All Android licenses accepted.

[√] Chrome - develop for the web
    • Chrome at C:\Program Files (x86)\Google\Chrome\Application\chrome.exe

[√] Visual Studio - develop Windows apps (Visual Studio Community 2022 17.8.6)
    • Visual Studio at C:\Program Files\Microsoft Visual Studio\2022\Community
    • Visual Studio Community 2022 version 17.8.34525.116
    • Windows 10 SDK version 10.0.22621.0

[√] Android Studio (version 2022.1)
    • Android Studio at C:\Program Files\Android\Android Studio
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    • android-studio-dir = C:\Program Files\Android\Android Studio
    • Java version OpenJDK Runtime Environment (build 11.0.15+0-b2043.56-8887301)

[√] VS Code (version 1.82.2)
    • VS Code at C:\Users\PC-3030\AppData\Local\Programs\Microsoft VS Code
    • Flutter extension version 3.48.0

[√] Connected device (3 available)
    • Windows (desktop) • windows • windows-x64    • Microsoft Windows [Version 10.0.19045.3930]
    • Chrome (web)      • chrome  • web-javascript • Google Chrome 121.0.6167.161
    • Edge (web)        • edge    • web-javascript • Microsoft Edge 121.0.2277.112

[√] Network resources
    • All expected network resources are available.

• No issues found!
```