Binding SolidColorBrush.Color in a control template yields binding error

Describe the bug

A binding error occurs when my custom templated control is first loaded when binding a SolidColorBrush.Color to a styled property. The binding works fine after that.

To Reproduce

I have a basic control that inherits TemplatedControl and has a Color property on it:

public static readonly StyledProperty<Color> ColorProperty =
	AvaloniaProperty.Register<ArcadeControlBase, Color>(nameof(Color), Colors.Transparent);

public Color Color {
	get => GetValue(ColorProperty);
	set => SetValue(ColorProperty, value);
}

In the control’s template:

<Rectangle Width="10" Height="10">
	<Rectangle.Fill>
		<SolidColorBrush Color="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=Color}" />
	</Rectangle.Fill>
</Rectangle>

This yields an error in the VS Output tool window:

[Binding]Error in binding to '#00000000'.'Color': 'Null value in expression '{empty}' at '$self.TemplatedParent'.'(SolidColorBrush #59182880)

Expected behavior

There should be no binding error.

Desktop (please complete the following information):

• OS: Windows
• Version 11.0.0-preview2

[billhenn]

@maxkatz6 thank you for the additional information. I come from WPF and am new to Avalonia. This really threw me off for a half hour trying to figure out if I was doing something wrong before posting.

I would highly suggest that messages like this only be written to the Output if there is a legit issue. I (and most devs) try to keep my Output completely clean so that I can clearly identify when there are problems I need to address. It’s really distracting to see the Output get clogged up with a ton of these messages, and makes it harder to identify real problems.

Considering how many others have reported similar things, hopefully that’s an indication that some kind of suppression of this message is needed. Appreciate it!

[lukaszossowski]

I would highly suggest that messages like this only be written to the Output if there is a legit issue.

This is particularly important, because apart from visual clutter, it makes it much harder to spot actual binding errors that are displayed there.

More context: #9219 (comment)

Wouldn’t it be possible to filter the messages? They do seem to all contain

'Null value in expression '{empty}'