NavigationView throws an exception when change the SelectedItem in code

Describe the bug Hi, I tried to change the SelectedItem of the NavigationView Control in code but i get an exception, I tried two different codes:

myNavigatoinView.SelectedItem = oneNavigationViewItem;

and

oneNavigationViewItem.IsSelected = true;

Both codes return the following exception:

System.NullReferenceException HResult=0x80004003 Message=Object reference not set to an instance of an object. Source=FluentAvalonia StackTrace: at FluentAvalonia.UI.Controls.SelectionModel.<>c.<get_SelectedItems>b__39_1(List1 infos, Int32 index) at FluentAvalonia.UI.Controls.SelectedItems2.get_Item(Int32 index) at FluentAvalonia.UI.Controls.SelectionModel.get_SelectedItem() at FluentAvalonia.UI.Controls.NavigationView.OnSelectionModelSelectionChanged(Object sender, SelectionModelSelectionChangedEventArgs e) at FluentAvalonia.UI.Controls.SelectionModel.OnSelectionChanged(SelectionModelSelectionChangedEventArgs e) at FluentAvalonia.UI.Controls.SelectionModel.EndOperation() at FluentAvalonia.UI.Controls.SelectionModel.Operation.Dispose() at FluentAvalonia.UI.Controls.SelectionModel.SelectAt(IndexPath index) at FluentAvalonia.UI.Controls.NavigationView.UpdateSelectionModelSelection(IndexPath ip) at FluentAvalonia.UI.Controls.NavigationView.OnNavigationViewItemIsSelectedPropertyChanged(AvaloniaPropertyChangedEventArgs args) at Avalonia.Reactive.LightweightObservableBase1.PublishNext(T value) at Avalonia.AvaloniaObject.RaisePropertyChanged[T](AvaloniaPropertyChangedEventArgs1 change) at Avalonia.AvaloniaObject.Avalonia.PropertyStore.IValueSink.ValueChanged[T](AvaloniaPropertyChangedEventArgs1 change) at Avalonia.ValueStore.NotifyValueChanged[T](AvaloniaProperty1 property, Optional1 oldValue, BindingValue1 newValue, BindingPriority priority) at Avalonia.ValueStore.SetValue[T](StyledPropertyBase1 property, T value, BindingPriority priority) at Avalonia.AvaloniaObject.SetValue[T](StyledPropertyBase1 property, T value, BindingPriority priority) at Avalonia.Controls.ListBoxItem.set_IsSelected(Boolean value) at Nimloth.Views.MainView.ChangeNavContent(NavigationViewItem nvi) in C:\Users\guilh\Documents\Acadêmico\VisualStudio\Nimloth\Nimloth Avalonia\Views\MainView.axaml.cs:line 191

Desktop/Platform (please complete the following information):

• OS: Windows 10
• FluentAvalonia Version [e.g. 1.3.4]
• Avalonia Version [e.g. 0.10.14]

[amwx]

I think this issue is related to ReactiveUI. Replacing the ReactiveCommand.Create with a basic ICommand implementation and the null ref issue went away. This would also align with why the click event works without issue

I don’t like nor use RxUI so I don’t know much about it, but IIRC it has it’s own task scheduler which might be causing some weird behavior leading to the null ref.

[amwx]

How did you set up the NavigationView? Binding or hard-coded items? A minimal repro would be great or at least a little more context so I can try to reproduce the error