@ladjs/i18n / i18n-locales silently broken by webpack 5.108.x — all emails fail with empty locale list

[daniel5150]

Bug report

Summary

A webpack regression introduced between v5.104.1 and v5.108.0 causes the i18n-locales JSON array (a transitive dependency of email-templates via @ladjs/i18n) to be emitted as an empty stub (module.exports = []) when bundled with usedExports: true. This makes every new I18N({ locales: ['de', 'en'] }) call throw Invalid locales: de, en at render time, causing the mailer to silently skip every email job.

Dependency chain

email-templates → @ladjs/i18n → i18n-locales (JSON array, last published 2021)

Root cause

With optimization.usedExports: true and sideEffects: false, webpack 5.108.x incorrectly treats individual array elements as named exports, finds none referenced, and stubs the entire module as []. A bug report has been filed with webpack: webpack/webpack#21426

Impact

• All email rendering silently fails — no error surfaced to callers, jobs report { sent: true }
• The build stays green (no compilation error or warning)
• Affects any project that bundles email-templates with webpack's usedExports optimization enabled

Workarounds (for users)

1. Pin webpack to 5.104.1 in resolutions
2. Add { test: /\.json$/, sideEffects: true } to webpack.module.rules

Suggested fix for this library

1. Add "sideEffects": true to i18n-locales/package.json — one-liner PR to ladjs/i18n-locales
2. Replace @ladjs/i18n with i18next — actively maintained, same dot-notation JSON locale format, identical t(key) API, not affected by this regression

Environment

• email-templates: 13.0.1
• @ladjs/i18n: 10.0.0
• i18n-locales: 0.0.5 (no updates since 2021)
• webpack: 5.108.4