fix: fix types for PackageJson exports

[pi0]

Fixes regression from #183

Exports field can be string or a nested object. But not an array of string. Passes tests for vue.js case at least.

[sxzz]

According to nodejs doc, it can be an array, and TS resolves it.

[sxzz]

https://nodejs.org/docs/latest/api/packages.html#exports

[pi0]

@sxzz Yes i saw that. But do you have a package example with it or link to spec how it works when array passed? (we can add back string[] but i need to make sure now)

[pi0]

Update: Found it in resolution algorithm (PACKAGE_EXPORTS_RESOLVE) so strange that there is limited info about it and i've never saw it in any package..

PS it seems about subpaths?

[pi0]

@sxzz Added back array type with correct specs (it should be only for subpaths and can be either string or object) seems good to you?

[sxzz]

I created a minimal reproduction: https://stackblitz.com/edit/vitejs-vite-jmzo3v?file=index.ts&terminal=dev

Run pnpm install && pnpm tsc, and you'll see that index.d.ts is generated with the correct types, inferred from pkg/b.d.ts. The pkg/package.json is:

{
  "name": "test-pkg",
  "exports": ["./a.d.ts", "./b.d.ts", "./c.d.ts"]
}

This demonstrates that TypeScript can always resolve array-type exports, whether they are in the root path or a subpath.

[pi0]

Thanks. I also confirmed with node resolution that does resolve array even more strange...

(updated PR to also include top level array 👍🏼 )