Integrating AvaloniaEdit into a Visual Studio extension

[stigzler]

Hi all. I'm kinda on the cusp of my capabilities as trying to shift over to WPF/MVVM and doing so via developing a small VS extension that allows users to view and edit Gists.

I'm looking for a WPF control that does syntax highlighting, but that can also accommodate light/dark themes. I tried AvalonEdit, but it didn't seem to be geared for dark themes. That led me here.

However, I tried the "Getting Started" guide here but go stuck on a few issues. You can see the project I'm working on here

1. It says "Create an empty Avalonia application." I can't do that as I'm trying to integrate it into my extension. Is it possible to integrate it non-the less?
2. It says "Include the needed styles into your <Application.Styles> in your App.xaml" - given it's a VS Extension - there is no App.xaml. I think it mirrors the UserControl project structure a lot. Where would I put the StyleInclude ??
3. I've nuget'd Avalonia.AvaloniaEdit and AvaloniaEdit.TextMate, and included xmlns:AvaloniaEdit="clr-namespace:AvaloniaEdit;assembly=AvaloniaEdit" at the top, but when I try to include the control vai xaml, I get:

The relevant xaml here, bottom of page

Apologies as this may be my wpf/mvvm newbiness, or just missing something simple regarding AvaloniaEdit. All the relevant Avalonia libraries are getting built to the build directory, so I'm struggling to understand why VS is struggling with the referencing.

Shame all this, as it does look perfect. Any help appreciated.