[Node 19 + ESM + PNP] ERR_MODULE_NOT_FOUND

[rtritto]

Search Terms

I'm starting a new project with yarn berry (Plug'n'Play enabled) and using ESM to test Node 19 features.

Expected Behavior

No ERR_MODULE_NOT_FOUND error

Actual Behavior

C:\<PROJECT_PATH>\test-pnp-node\.yarn\__virtual__\ts-node-virtual-6c4c0611aa\3\Users\<USER>\AppData\Local\Yarn\Berry\cache\ts-node-npm-10.9.1-6c268be7f4-9.zip\node_modules\ts-node\dist-raw\node-internal-modules-esm-resolve.js:757
  throw new ERR_MODULE_NOT_FOUND(packageName, fileURLToPath(base));
        ^
CustomError: Cannot find package 'undici' imported from C:\<PROJECT_PATH>\test-pnp-node\example.ts
    at packageResolve (C:\<PROJECT_PATH>\test-pnp-node\.yarn\__virtual__\ts-node-virtual-6c4c0611aa\3\Users\<USER>\AppData\Local\Yarn\Berry\cache\ts-node-npm-10.9.1-6c268be7f4-9.zip\node_modules\ts-node\dist-raw\node-internal-modules-esm-resolve.js:757:9)
    at moduleResolve (C:\<PROJECT_PATH>\test-pnp-node\.yarn\__virtual__\ts-node-virtual-6c4c0611aa\3\Users\<USER>\AppData\Local\Yarn\Berry\cache\ts-node-npm-10.9.1-6c268be7f4-9.zip\node_modules\ts-node\dist-raw\node-internal-modules-esm-resolve.js:798:18)
    at Object.defaultResolve (C:\<PROJECT_PATH>\test-pnp-node\.yarn\__virtual__\ts-node-virtual-6c4c0611aa\3\Users\<USER>\AppData\Local\Yarn\Berry\cache\ts-node-npm-10.9.1-6c268be7f4-9.zip\node_modules\ts-node\dist-raw\node-internal-modules-esm-resolve.js:912:11)
    at C:\<PROJECT_PATH>\test-pnp-node\.yarn\__virtual__\ts-node-virtual-6c4c0611aa\3\Users\<USER>\AppData\Local\Yarn\Berry\cache\ts-node-npm-10.9.1-6c268be7f4-9.zip\node_modules\ts-node\src\esm.ts:218:35
    at entrypointFallback (C:\<PROJECT_PATH>\test-pnp-node\.yarn\__virtual__\ts-node-virtual-6c4c0611aa\3\Users\<USER>\AppData\Local\Yarn\Berry\cache\ts-node-npm-10.9.1-6c268be7f4-9.zip\node_modules\ts-node\src\esm.ts:168:34)
    at C:\<PROJECT_PATH>\test-pnp-node\.yarn\__virtual__\ts-node-virtual-6c4c0611aa\3\Users\<USER>\AppData\Local\Yarn\Berry\cache\ts-node-npm-10.9.1-6c268be7f4-9.zip\node_modules\ts-node\src\esm.ts:217:14
    at addShortCircuitFlag (C:\<PROJECT_PATH>\test-pnp-node\.yarn\__virtual__\ts-node-virtual-6c4c0611aa\3\Users\<USER>\AppData\Local\Yarn\Berry\cache\ts-node-npm-10.9.1-6c268be7f4-9.zip\node_modules\ts-node\src\esm.ts:409:21)
    at resolve (C:\<PROJECT_PATH>\test-pnp-node\.yarn\__virtual__\ts-node-virtual-6c4c0611aa\3\Users\<USER>\AppData\Local\Yarn\Berry\cache\ts-node-npm-10.9.1-6c268be7f4-9.zip\node_modules\ts-node\src\esm.ts:197:12)
    at resolve (C:\<PROJECT_PATH>\test-pnp-node\.yarn\__virtual__\ts-node-virtual-6c4c0611aa\3\Users\<USER>\AppData\Local\Yarn\Berry\cache\ts-node-npm-10.9.1-6c268be7f4-9.zip\node_modules\ts-node\src\child\child-loader.ts:15:39)
    at nextResolve (node:internal/modules/esm/hooks:654:28)

Steps to reproduce the problem

• yarn init -y
• yarn set version canary
• yarn add undici typescript ts-node @types/node
• in package.json
  • add "type": "module"
  • change main to example.ts (optional/useless step)
• in .yarnrc.yml add nodeLinker: pnp (optional/useless step, Plug'n'Play is already enabled by default)
• create tsconfig.json file:

{
  "compilerOptions": {
    "esModuleInterop": true,  // optional/irrelevant
    "target": "ESNext",
    "module": "ESNext",
    "moduleResolution": "nodenext"  // irrelevant using node or bundler
  },
  "ts-node": {
    "esm": true
    // "experimentalSpecifierResolution": "node"  // optional/irrelevant
  }
}

• create example.ts file

import { request } from 'undici'

request('')

• yarn ts-node example.ts

Minimal reproduction

https://github.com/rtritto/ts-node-repros/tree/test-pnp-node

Specifications

• ts-node version: 10.9.1

• node version: 19.8.1

• TypeScript version: 5.0.2

• package.json:

{
  "name": "test-pnp-node",
  "version": "1.0.0",
  "main": "index.ts",
  "type": "module",
  "license": "MIT",
  "packageManager": "yarn@4.0.0-rc.40",
  "dependencies": {
    "@types/node": "^18.15.3",
    "ts-node": "^10.9.1",
    "typescript": "^5.0.2",
    "undici": "^5.21.0"
  }
}

• Operating system and version:
  Windows
• If Windows, are you using WSL or WSL2?:
  No
• Correctly work with nodeLinker: node-modules

[rtritto]

Fixed with:
yarn node --loader ts-node/esm --loader ./.pnp.loader.mjs example.ts

Source

Related change

[rtritto]

@cspotcode should ts-node autoinclude double loader (.pnp.loader.mjs when project is yarn berry based) when PnP is enabled and when command ts-node example.ts is used?

I think that initial post of #1007 should be updated with PnP case.

[bafu]

Yarn PNP has not supported ESM. There are some temporary solutions:

1. Rollback to node_modules by adding nodeLinker: node-modules in .yarnrc.yml.

   For the details, you can check the explanation from the Yarn upstream.

2. Enable experimental ESM loader by adding pnpEnableEsmLoader: true in .yarnrc.yml.

   For the details, you can check these comments: comment 1, comment 2

3. Enable experimental ESM loader by adding "type": "module" in package.json.

After any modification above, run yarn install again to ensure Yarn generates the necessary assistant files for you.