How to set article to default language if there is no translation for current language?

I have a problem when i add new language, and for that language there is no translation for article then i got an error. This is my code for article translation, so what i want is if there is no translation for current_language_id(if there is no that id in translation) to return translations for default_language_id.

$default_language_id = 1;
 $article_trans = $article->translations()->whereHas('language',function($query) use($current_language_id){
        $query->where('id','=',$current_language_id);
      })->first();

via Chebli Mohamed