Expo/Metro warning: invalid `exports` in `libphonenumber-js/min/metadata` (targets must start with "./")

What happened

When running an Expo app that depends on react-phone-number-input@3.4.12 (which uses libphonenumber-js), Metro prints this warning:

WARN The package <MY_APP_ROOT>/node_modules/libphonenumber-js/min/metadata contains an invalid package.json configuration. Consider raising this issue with the package maintainer(s). Reason: One or more mappings for subpaths defined in "exports" are invalid. All values must begin with "./". Falling back to file-based resolution.

The app continues to work, but the warning appears on every cold start.

Repro steps

npx create-expo-app myapp
npm i react-phone-number-input@3.4.12

Import anything from the package, e.g.:

import PhoneInput from 'react-phone-number-input'

npx expo start → open the app and observe the Metro warning above.

Environment

Expo (SDK 53+)
Metro (package exports enabled)
Platforms: iOS / Android / Web (warning is shown in Metro logs)
react-phone-number-input: 3.4.12
libphonenumber-js: as installed via the dependency above

Why this happens

libphonenumber-js includes a nested package at min/metadata whose package.json contains exports mappings that point outside that subpackage via ../../.... Per Node’s package exports rules, export targets must be relative paths that start with "./" (and must not traverse up with ..). Metro enforces this, warns, and then falls back to legacy file-based resolution so the app still runs.

An example of the problematic mapping in min/metadata/package.json:

{
  "exports": {
    ".": {
      "types": "../../metadata.min.json.d.ts",
      "import": "../../metadata.min.json.js",
      "require": "../../metadata.min.json"
    }
  }
}

Because the subpackage root is min/metadata/, those ../../ targets violate the "./" requirement.

Suggested fixes

Any of the following would remove the warning and make the package spec-compliant:

Option A (preferred): Expose metadata via the root package’s exports without a nested subpackage:

{
  "name": "libphonenumber-js",
  "exports": {
    "./min/metadata": {
      "types": "./metadata.min.json.d.ts",
      "import": "./metadata.min.json.js",
      "require": "./metadata.min.json"
    }
    // Optionally the same for: ./max/metadata, ./mobile/metadata
  }
}

Option B: Keep the nested min/metadata package, but make its files local and its exports targets start with "./" (would require duplicating or moving the files into that folder)

{
  "name": "libphonenumber-js/min/metadata",
  "exports": {
    ".": {
      "types": "./metadata.min.json.d.ts",
      "import": "./metadata.min.json.js",
      "require": "./metadata.min.json"
    }
  }
}

References

Node.js docs on "exports" target formats (targets must start with ./): https://nodejs.org/api/packages.html#exports
Metro package exports background (warning & fallback behavior): https://metrobundler.dev/docs/configuration/#unstable_enablepackageexports-experimental

Thanks for taking a look! I’m happy to test a prerelease or proposed fix.

Expo/Metro warning: invalid exports in libphonenumber-js/min/metadata (targets must start with "./")