Repository: flutter
Issue: Late nullable callback causes compilation error in web only
Labels: dependency: dart,platform-web,has reproducible steps,P2,team-web,triaged-web,dependency:dart-triaged,found in release: 3.24,found in release: 3.25

### Steps to reproduce

1. Create a new flutter app
2. Paste the attached code in main.dart
3. Run the application in Chrome or Edge

### Expected results

The app should run in Chrome/Edge as it does in Windows:
```
Launching lib\main.dart on Windows in debug mode...
√ Built build\windows\x64\runner\Debug\repro.exe
Connecting to VM Service at ws://127.0.0.1:63582/Te-PSxNQZzQ=/ws
Connected to the VM Service.
Lost connection to device.

Exited.
```

### Actual results

Notice the error appears only in the callback defined as late.

```
Launching lib\main.dart on Chrome in debug mode...
lib/main.dart:153:73: Error: Can't use an expression of type 'void Function()?' as a function because it's potentially null.
Try calling using ?.call instead.
          onChanged: _koCallback == null ? null : (value) => _koCallback(),
                                                                        ^
Failed to compile application.

Exited (1).
```

### Code sample

<details open><summary>Code sample</summary>

```dart
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 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,
            ),
            CheckField(),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

typedef CheckFieldValueChanged = void Function(bool value);
typedef Callback = void Function();

class CheckField extends StatelessWidget {
  late final Callback? _koCallback;
  final Callback? _okCallback;

  CheckField({
    Callback? okCallback,
    Callback? koCallback,
    super.key,
  }) : _okCallback = okCallback {
    _koCallback = koCallback;
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Checkbox(
          value: true,
          onChanged: _okCallback == null ? null : (value) => _okCallback(),
        ),
        Checkbox(
          value: true,
          onChanged: _koCallback == null ? null : (value) => _koCallback(),
        ),
      ],
    );
  }
}

```

</details>


### Screenshots or Video

_No response_

### Logs

_No response_

### Flutter Doctor output

<details open><summary>Doctor output</summary>

```console
Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel stable, 3.24.1, on Microsoft Windows [Version 10.0.22621.4037], locale en-US)
[√] Windows Version (Installed version of Windows is version 10 or higher)
[√] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
[√] Chrome - develop for the web
[√] Visual Studio - develop Windows apps (Visual Studio Professional 2022 17.10.1)
[√] Android Studio (version 2023.2)
[√] VS Code, 64-bit edition (version 1.92.2)
[√] Connected device (3 available)
[√] Network resources
```

</details>