No error reported on invalid `xmlns`

[MartinZikmund]

Current behavior

When the following is used:

<Grid xmlns:unoui="using:Uno.UI.Xaml.Controls.Whatever" >
	<TextBox unoui:TextBox.IsPointerCaptureRequired="True" Width="100" />
</Grid>

There is no error reported and the control loads ok, but the attached property clearly does not exist.

Expected behavior

Error should be thrown

How to reproduce it (as minimally and precisely as possible)

No response

Workaround

Can be reproduced by pasting the code in Samples app Playground

Works on UWP/WinUI

None

Environment

Uno.UI / Uno.UI.WebAssembly / Uno.UI.Skia, Uno.WinUI / Uno.WinUI.WebAssembly / Uno.WinUI.Skia

NuGet package version(s)

No response

Affected platforms

No response

IDE

No response

IDE version

No response

Relevant plugins

No response

Anything else we need to know?

No response