"Value is null" error spam when binding to an element

[TomEdwardsEnscape]

Describe the bug

When binding to $self or to a named element (e.g #MyButton), the binding system emits a log message saying that "Value is null". In our real application, we have an ItemsControl which leads to hundreds of these messages being emitted, noticeably affecting performance.

The binding works fine though.

To Reproduce

Add this XAML to any window and compile:

<Button Content="{Binding $self.Flyout.Placement}">
	<Button.Flyout>
		<MenuFlyout Placement="AnchorAndGravity">
			
		</MenuFlyout>
	</Button.Flyout>
</Button>

This will appear in the log output:

[Binding]An error occurred binding 'Content' to 'Flyout.Placement' at 'Flyout': 'Value is null.' (Button #5560998)

Expected behavior

No error messages

Avalonia version

11.1.0-beta2

OS

No response

Additional context

No response