[error] A message on the flutter/lifecycle channel was discarded before it could be handled.

What happened?

this code sample works locally both with flutter run -d chrome / flutter run -d chrome --release and served with dhttpd (see here), but fails on dartpad

Steps to reproduce problem

click on this link

Additional info

Browser

• Chrome (web) • chrome • web-javascript • Google Chrome 120.0.6099.71

Are you using any extensions/plugins that affect website behavior (particularly those that affect iframes, such as ad blockers)?

Are there any warnings or errors in your browser's JavaScript console? If so, paste them below:

Uncaught (in promise) Error: SecurityError: Failed to read the 'localStorage' property from 'Window': The document is sandboxed and lacks the 'allow-same-origin' flag.

    at Object.createErrorWithStack (errors.dart:329:10)
    at Error._throw (core_patch.dart:265:28)
    at Error.throwWithStackTrace (errors.dart:120:5)
    at async._AsyncCallbackEntry.new.callback (zone.dart:1386:11)
    at Object._microtaskLoop (schedule_microtask.dart:40:11)
    at _startMicrotaskLoop (schedule_microtask.dart:49:5)
    at async_patch.dart:181:7

Machine

                    'c.          francesco@Francescos-MacBook-Air.local
                 ,xNMM.          --------------------------------------
               .OMMMMo           OS: macOS 14.6.1 23G93 arm64
               OMMM0,            Host: MacBookAir10,1
     .;loddo:' loolloddol;.      Kernel: 23.6.0
   cKMMMMMMMMMMNWMMMMMMMMMM0:    Uptime: 10 days, 23 mins
 .KMMMMMMMMMMMMMMMMMMMMMMMWd.    Packages: 180 (brew)
 XMMMMMMMMMMMMMMMMMMMMMMMX.      Shell: zsh 5.9
;MMMMMMMMMMMMMMMMMMMMMMMM:       Resolution: 1440x900
:MMMMMMMMMMMMMMMMMMMMMMMM:       DE: Aqua
.MMMMMMMMMMMMMMMMMMMMMMMMX.      WM: Quartz Compositor
 kMMMMMMMMMMMMMMMMMMMMMMMMWd.    WM Theme: Blue (Dark)
 .XMMMMMMMMMMMMMMMMMMMMMMMMMMk   Terminal: WarpTerminal
  .XMMMMMMMMMMMMMMMMMMMMMMMMK.   CPU: Apple M1
    kMMMMMMMMMMMMMMMMMMMMMMd     GPU: Apple M1
     ;KMMMMMMMWXXWMMMMMMMk.      Memory: 1507MiB / 8192MiB
       .cooc,.    .,coo:.

Your code

import 'package:flutter/foundation.dart' show ValueListenable;
import 'package:shared_preferences/shared_preferences.dart'
    show SharedPreferences;
import 'package:flutter/material.dart';

void main() async {
  final counter = await SharedCounter.instance();
  runApp(
    MaterialApp(
      home: Scaffold(
        body: Center(
          child: ValueListenableBuilder<int>(
            valueListenable: counter,
            builder: (context, count, _) => Text('$count'),
          ),
        ),
        floatingActionButton: FloatingActionButton(
          onPressed: () => counter.value++,
          tooltip: 'Increment',
          child: const Icon(Icons.add),
        ),
      ),
    ),
  );
}

abstract class Counter extends ValueListenable<int> with ChangeNotifier {
  @override
  int get value;
  set value(int value);
}

final class SharedCounter extends Counter {
  SharedCounter._(
    this._prefs,
    String key,
    this.initialValue,
  ) : _key = key;

  final SharedPreferences _prefs;
  final String _key;
  final int initialValue;

  static Future<SharedCounter> instance({
    String key = 'COUNTER',
    initialValue = 0,
  }) async =>
      SharedCounter._(
        await SharedPreferences.getInstance(),
        key,
        initialValue,
      );

  @override
  int get value => _prefs.getInt(_key) ?? initialValue;

  @override
  set value(int value) {
    _prefs.setInt(_key, value);
    notifyListeners();
  }
}

DartPad's output

A message on the flutter/lifecycle channel was discarded before it could be handled.
This happens when a plugin sends messages to the framework side before the framework has had an opportunity to register a listener. See the ChannelBuffers API documentation for details on how to configure the channel to expect more messages, or to expect messages to get discarded:
  https://api.flutter.dev/flutter/dart-ui/ChannelBuffers-class.html

dart-lang / dart-pad

[error] A message on the flutter/lifecycle channel was discarded before it could be handled. #3046