i18next: saveMissingTo only saves current language

🐛 Bug Report

when fallbackLng:false, saveMissing: true and saveMIssingTo: 'all' is set, missing keys only being added to current language instead of all supported languages.

To Reproduce

i18n.js

import i18n from 'i18next';
import Backend from 'i18next-fs-backend';
import {resolve, join} from 'path';
import {lstatSync, readdirSync} from 'fs';

const localePath = resolve('./locales');

i18n
    .use(Backend)
    .init({
        backend: {
            allowMultiLoading: true,
            addPath: `${localePath}/{{lng}}/{{ns}}.json`,
            loadPath: `${localePath}/{{lng}}/{{ns}}.json`
        },
        preload: readdirSync(localePath).filter((fileName) => {
            const joinedPath = join(localePath, fileName);
            const isDirectory = lstatSync(joinedPath).isDirectory();
            return isDirectory;
        }),
        ns: readdirSync(`${localePath}/en`).filter((fileName) => {
            const joinedPath = join(`${localePath}/en`, fileName);
            const isDirectory = lstatSync(joinedPath).isDirectory();
            return !isDirectory;
        }).map(file => file.replace(/\.json/, '')),
        load: 'all',
        updateMissing: true,
        lowerCaseLng: true,
        cleanCode: true,
        defaultNS: 'common',
        nonExplicitSupportedLngs: true,
        keySeparator: false,
        fallbackLng: false,
        debug: true,
        saveMissingTo: 'all',
        saveMissing: true,
        interpolation: {
            escapeValue: false
        },
        supportedLngs: ['en', 'tr', 'de']
    });

export default i18n;

with above configuration, I delete all exceptions.js files, ( also tested with empty exceptions.js), if I call for i18n.changeLanguage('de'); i18n.t('exceptions:user-not-found'), I can see exceptions.js file gets generated in /locales/de/ folder. but even though it is set to all it does not create same exceptions file in other supported languages. The only way to generate them is to change language to missing one and re-trigger.

Expected behavior

when saveMissingTo is set to all it should create/update missing keys in all supported languages array. This will avoid developer to miss keys in different languages.

Your Environment

• runtime version: node v14, server-side-node + express
• i18next version: 21.6.16
• os: Linux