System.ArgumentNullException when removing an item from a BindableCollection binded to a FlyoutsControl

[jonferreira]

Using Caliburn.Micro.Demo add the following

ShellView.xaml

<Button MinWidth="90"
                    Margin="2"
                    cal:Message.Attach="[Event Click] = [Action RemoveFlyout]"
                    Content="Remove Bottom" />

ShellViewModel.cs

public void RemoveFlyout()
        {
            Flyouts.RemoveAt(0);
        }

error happens in FlyoutsControl.cs line 104

private void DetachHandlers(Flyout item)
        {
            var isOpenChanged = DependencyPropertyDescriptor.FromProperty(Flyout.IsOpenProperty, typeof(Flyout));
            var themeChanged = DependencyPropertyDescriptor.FromProperty(Flyout.ThemeProperty, typeof(Flyout));
            isOpenChanged.RemoveValueChanged(item, this.FlyoutStatusChanged);
            themeChanged.RemoveValueChanged(item, this.FlyoutStatusChanged);
        }

isOpenChanged.RemoveValueChanged(item, this.FlyoutStatusChanged); is returning System.ArgumentNullException because item is null

private void DetachHandlers(Flyout item)
        {
            if (item != null)
            {
                var isOpenChanged = DependencyPropertyDescriptor.FromProperty(Flyout.IsOpenProperty, typeof(Flyout));
                var themeChanged = DependencyPropertyDescriptor.FromProperty(Flyout.ThemeProperty, typeof(Flyout));
                isOpenChanged.RemoveValueChanged(item, this.FlyoutStatusChanged);
                themeChanged.RemoveValueChanged(item, this.FlyoutStatusChanged);
            }
        }

is an easy fix but most likely the wrong one...here ends my expertise. I'll wait for a comment from one of the Gurus out there...

[punker76]

fixed with #1681