Obscure error message when modifying property accessed by UI on timer thread

[Pdawg-bytes]

Describe the bug

Normally, when you access anything that the UI concerns from another thread, you have to go through the dispatcher. A member in the UWP Community Discord ran into this same problem, but was met with a very undescriptive error message, saying System.Runtime.InteropServices.COMException: "".

Though, I do recall seeing the proper error message before when this happened, but I don't remember how long ago that was.

Steps to reproduce the bug

https://github.com/Pdawg-bytes/WASDK-INPC-COMException-repro/tree/main
Clone this repository and run the app. Take note of the comments in App1/SystemViewModel.cs.

Expected behavior

When you attempt to access something like this, the error message should tell you that you need to use the Dispatcher to dispatch it to the UI thread.

Screenshots

Here's the undescriptive error message:

NuGet package version

WinUI 3 - Windows App SDK 1.6.0: 1.6.240829007

Windows version

Windows 11 (22H2): Build 22621

Additional context

No response

[lolametro]

This is very annoying.

It's not clear to me why the exception text is empty, as the HResult value is properly set to -2147417842 0x8001010E RPC_E_WRONG_THREAD. The plain old Win32Exception would automatically display a message like The application called an interface that was marshalled for a different thread..