It uses a new Roslyn API to dump SyntaxTree and IOperation's starting at a specific span of source code IIRC, and it shipped in one of the minor version after .NET 8.0.0 release, it took me a bit to get it working upon its release but by this time you should have the necessary SDK, though the relevant extension version may still be marked as pre-release hence my suggestion.
I messed with it a little more before going to bed. The prerelease version changed the error and at least felt like it was closer. But I also found there was a new SDK release in the last few days that I have not upgraded yet.
