Tinypool.version throws ReferenceError: __dirname is not defined (package is type: module)

[martin-k-m]

The problem

Tinypool.version throws ReferenceError: __dirname is not defined.

The package declares "type": "module", so Node loads dist/index.js as an ES module — and an ES module has no __dirname binding. The getter reads one.

Reproduce

npm i tinypool@2.1.2

probe.mjs:

import Tinypool from 'tinypool'
console.log(Tinypool.version)

$ node probe.mjs
ReferenceError: __dirname is not defined

I ran a control in the same file first — a bare __dirname reference, to confirm the scope really is an ES module rather than something my harness leaked:

control (bare __dirname here): ReferenceError
Tinypool.version THREW: ReferenceError: __dirname is not defined

Where

src/index.ts, in static get version():

static get version(): string {
  const { version } = JSON.parse(
    readFileSync(join(__dirname, '../package.json'), 'utf-8')
  )
  ...

which lands in dist/index.js:759 in the published 2.1.2 tarball. package.json has "type": "module" and dist/index.js is the only entry, so there is no CommonJS path to this code.

There is no createRequire or fileURLToPath shim in the emitted file — I grepped it — so nothing supplies __dirname at runtime.

Why it has probably gone unnoticed

version is the only thing reaching it. Everything else in the public API works, so a consumer only hits this if they read that property.

Fix

The usual ESM equivalent, e.g.

import { fileURLToPath } from 'node:url'
const here = dirname(fileURLToPath(import.meta.url))

or reading the version at build time. Happy to open a PR if you'd like one.

Notes

Found by an automated checker I'm building that flags CommonJS bindings in files Node resolves as ES modules. I verified this one by hand against the published 2.1.2 tarball before filing, and checked the open and closed issues for an existing report.