(feat) watch tsconfig and extended tsconfig

[jasonlyu123]

#1529

Steps:

1. use a proxy of extendedConfigCache to monitor referenced extendedConfig
2. watch the tsconfig and the extended config file.
3. if tsconfig is updated, delete the service.
4. if extended tsconfig is updated, delete the services extending the config file
5. update diagnostic and restart service if the deleted one is still used.

todo:
find a way to test this. currently thinking about adding another property to LanguageServiceDocumentContext. To allow mocking the ts.sys object so we can more easily test it without needing to try finally on the file system

[dummdidumm]

This is great! About testing this: I don't know either how else to test this other than either with a try-catch-finally and some hacky overwriting of ts.sys, or refactoring it so that we can test these things easier. I slightly prefer the "hack now, fix later" approach - in the long run it might be benefitial to make ts a paramater of all functions/classes that uses, which would mean people could more easily use their workspace version of TS, and maybe it also makes some parts of the browser support easier (you know more about that one than me, just a guess).

[dummdidumm]

I was at first confused why this is enough, until I realized that you don't need to explicitly restart the server because the next getService call will do this. Could you add a comment here and in watchConfigCallback about this?

[dummdidumm]

Code style: I would prefer it to have these added top level functions (at least the first two) inside createLanguageService. This would remove the need to expose extendedConfigPaths

[dummdidumm]

Is this ready for a final review and merge? It doesn't have tests now but I'm okay with this being untested for now

[jasonlyu123]

I added some tests with the virtual ts.sys . And also find that I never call the onProjectReloaded 😆. It only works because svelte-kit sync also creates .d.ts files which trigger onDidChangeWatchedFiles It's ready for final review and merge now.

[dummdidumm]

Nice!

I feel like we should revisit service.ts at some point, it feels like it has grown a little too much over the years, but I don't have a good idea how to refactor this into something that is easier to understand and more testable.