Loading additional translations when a lazy loaded module get's loaded

LazyModuleMissingTranslationHandler

import { Observable } from 'rxjs';
import { tap, refCount, publishReplay, map } from 'rxjs/operators';
import {
  MissingTranslationHandler,
  MissingTranslationHandlerParams
} from '@ngx-translate/core';

export class LazyModuleMissingTranslationHandler extends MissingTranslationHandler {
  translationsLoaded: { [language: string]: Observable<any> | boolean } = {};

  handle(params: MissingTranslationHandlerParams) {
    const key = params.key;
    const currentLang =
      params.translateService.currentLang ||
      params.translateService.defaultLang;
    const translateLoader = params.translateService.currentLoader;

    if (!currentLang) {
      return;
    }

    const status = this.translationsLoaded[currentLang];
    if (typeof status === 'undefined') {
      // load translations for language
      // when done set translationsLoaded[currentLang] to true
      const $translations = translateLoader.getTranslation(currentLang).pipe(
        tap(translations =>
          params.translateService.setTranslation(
            currentLang,
            translations,
            true
          )
        ),
        tap(() => (this.translationsLoaded[currentLang] = true)),
        publishReplay(),
        refCount()
      );

      // translations are being loaded, put observable in translationsLoaded[currentLang]
      this.translationsLoaded[currentLang] = $translations;
      // return observable for requested translation
      return $translations.pipe(
        map(translations =>
          params.translateService.getParsedResult(
            translations,
            key,
            params.interpolateParams
          )
        )
      );
    } else {
      if (typeof status !== 'boolean') {
        // translations are being loaded, return observable for requested translation
        return status.pipe(
          map(translations =>
            params.translateService.getParsedResult(
              translations,
              key,
              params.interpolateParams
            )
          )
        );
      }
    }
    return;
  }
}