Bug Report

When a TypeScript project specifies "module": "nodenext" (or "node12") in tsconfig.json, tsc emits errors saying it can't find imported modules or that the exports aren't the right types.

I've put together a demo that shows this with the "ip" and "nullthrows" packages. "ip" doesn't ship with TypeScript declarations and needs "@types/ip", while "nullthrows" comes with declarations. The precise errors are included below but in summary, tsc can't find "ip" and it thinks "nullthrows" is not callable despite the default export being a function.

Playing around, when I add "type": "module" to nullthrows's package.json, its error goes away. When I change ip's package.json from "main": "lib/ip" to "main": "lib/ip.js", its issue goes away. Writing this out, these are likely two different issues with the shared symptom of an ESM package not being able to import either of them.

🔎 Search Terms

esm module nodenext

🕗 Version & Regression Information

typescript@4.6.0-dev.20211110

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about modules. The issue is present in the 4.5.0 betas as well, though I understand that ESM support via nodenext/node12 is being deferred.

⏯ Playground Link

Minimal repo: https://github.com/ide/typescript-esm-demo. Dependencies are needed to show the effect.

💻 Code

import * as ip from 'ip';
import nullthrows from 'nullthrows';

export function getAddress(): string {
  return nullthrows(ip.address());
}

🙁 Actual behavior

tsc outputs:

index.ts:1:21 - error TS2307: Cannot find module 'ip' or its corresponding type declarations.

1 import * as ip from 'ip';
                      ~~~~

index.ts:5:10 - error TS2349: This expression is not callable.
  Type 'typeof import("/private/tmp/typescript-esm-demo/node_modules/nullthrows/nullthrows")' has no call signatures.

5   return nullthrows(ip.address());
           ~~~~~~~~~~


Found 2 errors.

🙂 Expected behavior

tsc should compile without errors.