Which package?

intl-messageformat@10.4.0

Describe the bug

intl-messageformat@10.4.0 package imports resolve to lib/index.js. This is a .js file in a package that doesn’t specify "type": "module". This makes it CJS, but it contains ESM syntax.

To Reproduce

Reproducible Steps/Repo

Steps to reproduce the behavior:

1. Install intl-messageformat@10.4.0

   npm install intl-messageformat@10.4.0

2. Create a script named script.mjs with the following content:

   import 'intl-messageformat'

3. Run it

   node ./script.mjs

4. See error

Expected behavior

Nothing

Screenshots

No screenshot, but a stack trace:

(node:47086) Warning: To load an ES module, set "type": "module" in the package.json or use the .mjs extension.
(Use `node --trace-warnings ...` to show where the warning was created)
node_modules/intl-messageformat/lib/index.js:6
import { IntlMessageFormat } from './src/core';
^^^^^^

SyntaxError: Cannot use import statement outside a module
    at internalCompileFunction (node:internal/vm:73:18)
    at wrapSafe (node:internal/modules/cjs/loader:1195:20)
    at Module._compile (node:internal/modules/cjs/loader:1239:27)
    at Module._extensions..js (node:internal/modules/cjs/loader:1329:10)
    at Module.load (node:internal/modules/cjs/loader:1133:32)
    at Module._load (node:internal/modules/cjs/loader:972:12)
    at ModuleWrap.<anonymous> (node:internal/modules/esm/translators:165:29)
    at ModuleJob.run (node:internal/modules/esm/module_job:193:25)

Node.js v19.9.0

Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context

The ESM files should be actual ESM. Since everything in the lib directory is ESM, the simplest solution would be to write lib/package.json with the following content:

{
  "type": "module"
}

Alternatively the .mjs extension should be used, and the .mts extension for TypeScript files.

Type definitions need to match as well. To fix this, the "exports" → ".' → "types" field needs to be removed.

Also ESM requires to use file extensions in the import.