translateService.use doesn't work for multiple lazy loaded components

[sergiubologa]

Current behavior

If you have an app with one base component and other 2 components which are lazy loaded the translateService.use function doesn't make the request to retrieve translation files.

Expected behavior

It should retrieve the translation files for each lazy loaded modules.

How do you think that we should fix this?

The issue is caused by this line:

// don't change the language if the language given is already selected
if (lang === this.currentLang) {
    return of(this.translations[lang]);
}

I'm not sure what would happen if the check is removed, but my first guess is to remove it. :)

Minimal reproduction of the problem with instructions

Here's a stackblitz demonstrating the issue: https://stackblitz.com/edit/angular-sm99qe-ngx-translate-lazy-load

Environment

ngx-translate version: 12.1.1
Angular version: 7.0.0.

[leon-marzahn]

Nothing should happen if you remove the check, it'll just load the translations again if you call translateService.use. Maybe there should be an additional check, to see what context you're in