No Typescript error for unresolved types in .d.ts files?

Question

For as long as I can remember, Typescript didn't warn about unresolved/undefined types in .d.ts files. I could run tsc and it wouldn't have any errors. I already have noImplicitAny enabled. This file is also in my tsconfig's include. Is this expected or is there an issue with my setup? Is there a way to make this an error?

Here's a related question specifically about VS Code (Is there a way to make VSCode show errors for unresolved types in .d.ts files?), I'm experiencing the same issue in VS Code, but even tsc has the issue.

Answer 1

I was looking for an answer to the same question. In my case, it turned out that I was using a framework (SvelteKit) that had skipLibCheck: true in the default tsconfig.json. So it wasn't just the imports: there was no type checking at all in my .d.ts files. Maybe this is the same for you?

Note that setting skipLibCheck: false (the default if it's not set) can have some other consequences relating to performance and possible conflicts between .d.ts files in your node_modules. See the documentation on skipLibCheck.