Async TypeScript plugin crashes TypeScript

[remcohaszing]

Given a project using project references, if the project has been built, the TypeScript language server crashes.

I noticed this while working on rehype-mdx-constant-elements. Coincidentally this project is related to MDX, but it doesn’t actually contain any MDX files.

By disabling VSCode extensions, I narrowed this down to the MDX extension. Everything works fine with the Astro, Svelte, and Vue extensions enabled. My conclusion was this is probably related to Volar’s createAsyncLanguageServicePlugin.

Based on further fiddling I discovered this crash only happens if the project has been built, or to put it differently, if tsc -b has been run in the project.

Doing some bisecting, I found out this is a regression in Volar 2.4.11. I made a reproduction in mdx-js/mdx-analyzer@2150422.

I narrowed it down to c115031