feat: warn on likely failed d.ts file generation

[dummdidumm]

emitDts now warns when it detects diagnostics that likely mean the d.ts file was not generated

[jasonlyu123]

The code for #2371 is 2742 but judging from https://github.com/microsoft/TypeScript/blob/main/src/compiler/transformers/declarations.ts there are 10+ more exceptions outside the 4000-4108 range. Do you think we should write a script to fetch it from this file or maybe try something like #2371 (comment)?

[dummdidumm]

Sounds good - let's try that! As for the diagnostic: TBH even for me, and even if the code wasn't transpiled, it's super confusing to really know what I should do after getting such an error message. So I wouldn't invest too much time into making them nicer.

[SystemParadox]

I literally ran into this last week and this patch would have saved a lot of time! I agree that just knowing that it failed (and which file) is the main thing. I think it's highly like that in practice you'll have to open it up in vscode to be able to work out what's going on anyway.