[Bug] Crash when spawning an ES module worker_thread

[aduh95]

• I'd be willing to implement a fix

Describe the bug

Yarn 2 crashes when loading a worker file written as ES module.

To Reproduce

const {promises: {writeFile}} = require(`fs`);

await packageJsonAndInstall({});

const WORKER_PATH = './worker.mjs';

await writeFile(WORKER_PATH, `
import { isMainThread, Worker } from "worker_threads";

if (isMainThread) {
  new Worker("${WORKER_PATH}");
} else {
  // Worker code here
}
`)

await expect(yarn('node', WORKER_PATH))
  .rejects.not.toThrow(`Must use import to load ES Module`);

Environment if relevant (please complete the following information):

• Node version [e.g. 8.15.0, 10.15.1, ...] 13.7.0
• Yarn version [e.g. 2.0.0-rc1, ...] master (cae4477)

Additional context

Node.js can load script workers as well as ES modules workers (although ESM is still experimental at time of writing). It uses the same resolution algorithm as non-worker file to pick EMS loader or CJS loader. To qualify as ESM, a file is either:

• using .mjs as extension.
• using .js as extension and the closest package.json contains type=module.

[yarnbot]

This issue reproduces on master:

Error: expect(received).rejects.not.toThrow(expected)

Expected substring: not "Must use import to load ES Module"
Received message:       "Command failed: /usr/bin/node /github/workspace/scripts/actions/../run-yarn.js node ./worker.mjs
internal/modules/cjs/loader.js:1029
  throw new ERR_REQUIRE_ESM(filename);
  ^

Error [ERR_REQUIRE_ESM]: Must use import to load ES Module: /tmp/tmp-27QR87OnDqLgxB/worker.mjs
    at Object.Module._extensions..mjs (internal/modules/cjs/loader.js:1029:9)
    at Module.load (internal/modules/cjs/loader.js:815:32)
    at Function.module_1.Module._load (/tmp/tmp-27QR87OnDqLgxB/.pnp.js:13581:14)
    at Function.Module.runMain (internal/modules/cjs/loader.js:1047:10)
    at internal/main/run_main_module.js:17:11 {
  code: 'ERR_REQUIRE_ESM'
}

"

      13579 | 
      13580 |     try {
    > 13581 |       module.load(modulePath);
            |              ^
      13582 |       hasThrown = false;
      13583 |     } finally {
      13584 |       if (hasThrown) {

      at Function.module_1.Module._load (.pnp.js:13581:14)
      at internal/main/run_main_module.js:17:11 {
        code: 'ERR_REQUIRE_ESM'
      }
    at Object.toThrow (/github/workspace/.yarn/cache/expect-npm-24.8.0-8c7640c562-2.zip/node_modules/expect/build/index.js:242:20)
    at module.exports (evalmachine.<anonymous>:19:16)
    at async /github/workspace/.yarn/cache/@arcanis-sherlock-npm-1.0.38-d4f5e2dbf3-2.zip/node_modules/@arcanis/sherlock/lib/executeRepro.js:56:13
    at async executeInTempDirectory (/github/workspace/.yarn/cache/@arcanis-sherlock-npm-1.0.38-d4f5e2dbf3-2.zip/node_modules/@arcanis/sherlock/lib/executeRepro.js:17:16)
    at async Object.executeRepro (/github/workspace/.yarn/cache/@arcanis-sherlock-npm-1.0.38-d4f5e2dbf3-2.zip/node_modules/@arcanis/sherlock/lib/executeRepro.js:24:12)
    at async ExecCommand.execute (/github/workspace/.yarn/cache/@arcanis-sherlock-npm-1.0.38-d4f5e2dbf3-2.zip/node_modules/@arcanis/sherlock/lib/commands/exec.js:25:38)
    at async ExecCommand.validateAndExecute (/github/workspace/.yarn/cache/clipanion-npm-2.0.0-rc.16-b9444aaf89-2.zip/node_modules/clipanion/lib/advanced/Command.js:161:26)
    at async Cli.run (/github/workspace/.yarn/cache/clipanion-npm-2.0.0-rc.16-b9444aaf89-2.zip/node_modules/clipanion/lib/advanced/Cli.js:74:24)
    at async Cli.runExit (/github/workspace/.yarn/cache/clipanion-npm-2.0.0-rc.16-b9444aaf89-2.zip/node_modules/clipanion/lib/advanced/Cli.js:83:28)

[merceyz]

Tracked in #638