TypeScript types are broken when using node10 moduleResolution

[TrevorBurnham]

After upgrading my Next.js app to superjson@2.2.5, I get this tsc error:

src/fetch.tsx:3:23 - error TS7016: Could not find a declaration file for module 'superjson'. '/my-project-dir/node_modules/superjson/dist/index.js' implicitly has an 'any' type.
  There are types at '/my-project-dir/node_modules/superjson/dist/index.d.ts', but this result could not be resolved under your current 'moduleResolution' setting. Consider updating to 'node16', 'nodenext', or 'bundler'.

3 import superJSON from "superjson";
                        ~~~~~~~~~~~

The invaluable arethetypeswrong checker confirms the issue:

$ npx @arethetypeswrong/cli --from-npm superjson@2.2.5

❌ Import resolved to JavaScript files, but no type declarations were found. https://github.com/arethetypeswrong/arethetypeswrong.github.io/blob/main/docs/problems/UntypedResolution.md


┌───────────────────┬─────────────┐
│                   │ "superjson" │
├───────────────────┼─────────────┤
│ node10            │ ❌ No types │
├───────────────────┼─────────────┤
│ node16 (from CJS) │ 🟢 (CJS)    │
├───────────────────┼─────────────┤
│ node16 (from ESM) │ 🟢 (ESM)    │
├───────────────────┼─────────────┤
│ bundler           │ 🟢          │
└───────────────────┴─────────────┘

Compare to 2.2.3:

$ npx @arethetypeswrong/cli --from-npm superjson@2.2.3

❌ Import resolved to JavaScript files, but no type declarations were found. https://github.com/arethetypeswrong/arethetypeswrong.github.io/blob/main/docs/problems/UntypedResolution.md


┌───────────────────┬─────────────┐
│                   │ "superjson" │
├───────────────────┼─────────────┤
│ node10            │ 🟢          │
├───────────────────┼─────────────┤
│ node16 (from CJS) │ ❌ No types │
├───────────────────┼─────────────┤
│ node16 (from ESM) │ 🟢 (ESM)    │
├───────────────────┼─────────────┤
│ bundler           │ 🟢          │
└───────────────────┴─────────────┘

So recent changes fixed one type issue, but broke existing types.

It's worth noting that "moduleResolution": "node10" is the default, and is effectively required by Next.js (it overwrites the moduleResolution value in tsconfig.json if you change it to something else). So it's safe to say that this type issue affects a large number of superjson consumers.

Relatedly, I sent a PR a while back to use tsup to build the correct types for all moduleResolution modes: #327

[Skn0tt]

Hi! Thanks for letting me know of the type failures. I greatly appreciate that you put the time not only into #327 but also this issue. Thank you! Revisiting your PR, I'm not confident that it'll be safe to ship, because it's quite a lot of change. And we just saw how brittle all this CJS/ESM stuff is.

Given our track record on making CJS work, I think the safest way forward is to revert the recent changes and turn this module back to ESM only.