[Bug]: Cancelling a task from an object in a command cause the application to crash

[SteezCram]

Describe the bug 🐞

I was developing an object to synchronize some files over the network. I want the user to be able to stop the synchronization. I ended up utilizing Task to achieve that and a CancellationTokenSource to cancel the task.

I use this documentation to achieve it: https://learn.microsoft.com/en-us/dotnet/standard/parallel-programming/task-cancellation

So far, everything works as it was intended. But when I try to stop the synchronization by using a ReactiveCommand, my application exit (see https://www.reactiveui.net/docs/handbook/default-exception-handler/). Despite catching the exception, the default exception handler triggered an exception because my task was canceled...

Step to reproduce

Simple object to reproduce:

class MyObject
{
    private CancellationTokenSource _cancellationTokenSource = new();

    public MyObject() { }

    public async Task<bool> StartAsync()
    {
        for (int i = 0; i < 100; i++)
        {            
            try
            {
                await BackgroundMethodAsync();
            }
            catch (OperationCanceledException ex)
            {
                return false;
            }
        }
        
        return true;
    }

    public async Task StopAsync()
    {
        _cancellationTokenSource.Cancel();
        // Wait task to finish
        await Task.Delay(10000);
        _cancellationTokenSource.Dispose();
    }

    private async Task BackgroundMethodAsync()
    {
        for (int i = 0; i < 100; i++)
        {
            _cancellationTokenSource.Token.ThrowIfCancellationRequested();
            await Task.Delay(10000);
        }
    }
}

Just create 2 commands that use both StartAsync and StopAsync. If you called StopAsync and you abord the task, it should close the application.

Reproduction repository

No response

Expected behavior

When catching the exception it should not exit the application.

Screenshots 🖼️

No response

IDE

Visual Studio 2022

Operating system

Windows

Version

Windows 11

Device

No response

ReactiveUI Version

13.2.10

Additional information ℹ️

The version of Avalonia 0.10.18 has been tested

[SteezCram]

EDIT: if the stop method is not a task, we do not have the bug

There is a new object that does not produce the bug:

class MyObject
{
    private CancellationTokenSource _cancellationTokenSource = new();

    public MyObject() { }

    public async Task<bool> StartAsync()
    {
        for (int i = 0; i < 100; i++)
        {            
            try
            {
                await BackgroundMethodAsync();
            }
            catch (OperationCanceledException ex)
            {
                _cancellationTokenSource.Dispose();
                return false;
            }
        }
        
        return true;
    }

    public void Stop()
    {
        _cancellationTokenSource.Cancel();
    }

    private async Task BackgroundMethodAsync()
    {
        for (int i = 0; i < 100; i++)
        {
            _cancellationTokenSource.Token.ThrowIfCancellationRequested();
            await Task.Delay(10000);
        }
    }
}

[ChrisPulman]

This should now be resolved, please raise a new issue with any new findings, many thanks

[github-actions]

This issue has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.