BindingOperations.GetBindingExpressionBase().UpdateSource() second time deletes ItemsSource

[TrevorDArcyEvans]

Describe the bug

Calling UpdateSource() second time deletes underlying ItemsSource which then causes a CRASH

To Reproduce

• start app

• click button Add keys (first time)

• [OBSERVED] nothing

• click button Add keys (second time)

• [OBSERVED] CRASH

  System.NullReferenceException: Object reference not set to an instance of an object.
     at AvaDic.ViewModels.MainWindowViewModel.AddKey() in /home/trevorde/dev/AvaDic/ViewModels/MainWindowViewModel.cs:line 35
     at CompiledAvaloniaXaml.XamlIlTrampolines.AvaDic:AvaDic.ViewModels.MainWindowViewModel+AddKey_0!CommandExecuteTrampoline(Object, Object)
     at Avalonia.Data.Core.ExpressionNodes.MethodCommandNode.Command.Execute(Object parameter)
     at Avalonia.Controls.Button.OnClick()
     at Avalonia.Controls.Button.OnPointerReleased(PointerReleasedEventArgs e)
     at Avalonia.Input.InputElement.<>c.<.cctor>b__32_9(InputElement x, PointerReleasedEventArgs e)
     at Avalonia.Interactivity.RoutedEvent`1.<>c__DisplayClass1_0`1.<AddClassHandler>g__Adapter|0(Object sender, RoutedEventArgs e)
     at Avalonia.Interactivity.RoutedEvent.<>c__DisplayClass23_0.<AddClassHandler>b__0(ValueTuple`2 args)
     at Avalonia.Reactive.AnonymousObserver`1.OnNext(T value)
     at Avalonia.Reactive.LightweightObservableBase`1.PublishNext(T value)
     at Avalonia.Reactive.LightweightSubject`1.OnNext(T value)
     at Avalonia.Interactivity.RoutedEvent.InvokeRaised(Object sender, RoutedEventArgs e)
     at Avalonia.Interactivity.EventRoute.RaiseEventImpl(RoutedEventArgs e)
     at Avalonia.Interactivity.EventRoute.RaiseEvent(Interactive source, RoutedEventArgs e)
     at Avalonia.Interactivity.Interactive.RaiseEvent(RoutedEventArgs e)
     at Avalonia.Input.MouseDevice.MouseUp(IMouseDevice device, UInt64 timestamp, IInputRoot root, Point p, PointerPointProperties props, KeyModifiers inputModifiers, IInputElement hitTest)
     at Avalonia.Input.MouseDevice.ProcessRawEvent(RawPointerEventArgs e)
     at Avalonia.Input.MouseDevice.ProcessRawEvent(RawInputEventArgs e)
     at Avalonia.Input.InputManager.ProcessInput(RawInputEventArgs e)
     at Avalonia.Controls.TopLevel.<>c.<HandleInput>b__145_0(Object state)
     at Avalonia.Threading.Dispatcher.Send(SendOrPostCallback action, Object arg, Nullable`1 priority)
     at Avalonia.Controls.TopLevel.HandleInput(RawInputEventArgs e)
     at Avalonia.X11.X11Window.DispatchInput(RawInputEventArgs args)
     at Avalonia.RawEventGrouper.Dispatch(RawInputEventArgs ev)
     at Avalonia.ManualRawEventGrouperDispatchQueue.DispatchNext()
     at Avalonia.X11.X11PlatformThreading.RunLoop(CancellationToken cancellationToken)
     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.StartCore(String[] args)
     at Avalonia.Controls.ApplicationLifetimes.ClassicDesktopStyleApplicationLifetime.Start(String[] args)
     at Avalonia.ClassicDesktopStyleApplicationLifetimeExtensions.StartWithClassicDesktopLifetime(AppBuilder builder, String[] args, Action`1 lifetimeBuilder)
     at AvaDic.Program.Main(String[] args) in /home/trevorde/dev/AvaDic/Program.cs:line 12

AvaDic.zip

Expected behavior

• [EXPECTED] no crash
• [EXPECTED] ItemsSource aka DataMap not to be null

Avalonia version

11.2.4

OS

Linux

Additional context

• Linux Mint 21.2
• Avalonia --> 11.2.4
• Avalonia.Desktop --> 11.2.4
• Avalonia.Themes.Fluent --> 11.2.4
• Avalonia.Fonts.Inter --> 11.2.4
• Avalonia.Diagnostics --> 11.2.4">
• CommunityToolkit.Mvvm --> 8.4.0

/~https://github.com/TrevorDArcyEvans/AvaDic