Did try running on macOS and when trying to attach to process I get exception:
Unhandled exception. System.ArgumentException: Process with an Id of 58669 is not running.
at System.Diagnostics.Process.GetProcessById(Int32 processId, String machineName)
at GummyCat.ProcessPickerDialog.<>c.<.ctor>b__0_1(Int32 pid) in /Users/wieslawsoltes/GitHub/GummyCat/src/GummyCat/ProcessPickerDialog.axaml.cs:line 22
at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.ToArray()
at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
at System.Linq.OrderedEnumerable`1.GetEnumerator()+MoveNext()
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
at System.Collections.ObjectModel.ObservableCollection`1..ctor(IEnumerable`1 collection)
at GummyCat.ProcessPickerDialog..ctor() in /Users/wieslawsoltes/GitHub/GummyCat/src/GummyCat/ProcessPickerDialog.axaml.cs:line 20
at GummyCat.MainWindow.MenuAttach_Click(Object sender, RoutedEventArgs e) in /Users/wieslawsoltes/GitHub/GummyCat/src/GummyCat/MainWindow.axaml.cs:line 598
at System.Threading.Tasks.Task.<>c.<ThrowAsync>b__128_0(Object state)
at Avalonia.Threading.SendOrPostCallbackDispatcherOperation.InvokeCore()
at Avalonia.Threading.DispatcherOperation.Execute()
at Avalonia.Threading.Dispatcher.ExecuteJob(DispatcherOperation job)
at Avalonia.Threading.Dispatcher.RunJobs(Nullable`1 priority, CancellationToken cancellationToken)
at Avalonia.Threading.Dispatcher.RunJobs(Nullable`1 priority)
at Avalonia.Native.WindowBaseImpl.WindowBaseEvents.Avalonia.Native.Interop.IAvnWindowBaseEvents.RunRenderPriorityJobs()
at Avalonia.Native.Interop.Impl.__MicroComIAvnWindowBaseEventsVTable.RunRenderPriorityJobs(Void* this)
--- End of stack trace from previous location ---
at Avalonia.Native.DispatcherImpl.RunLoop(CancellationToken token)
at Avalonia.Threading.DispatcherFrame.Run(IControlledDispatcherImpl impl)
at Avalonia.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
at Avalonia.Threading.Dispatcher.MainLoop(CancellationToken cancellationToken)
at Avalonia.Controls.ApplicationLifetimes.ClassicDesktopStyleApplicationLifetime.Start(String[] args)
at Avalonia.ClassicDesktopStyleApplicationLifetimeExtensions.StartWithClassicDesktopLifetime(AppBuilder builder, String[] args, Action`1 lifetimeBuilder)
at GummyCat.Program.Main(String[] args) in /Users/wieslawsoltes/GitHub/GummyCat/src/GummyCat/Program.cs:line 12
Did try running on macOS and when trying to attach to process I get exception: