Some clean up stuff

src/app/service/language.service.spec.ts

@@ -14,12 +14,15 @@ describe('LanguageService', () => {
     return TestBed.inject(LanguageService);
   }
 
+  const documentLanguage = document.documentElement.lang;
+
   beforeEach(() => {
     localStorage.clear();
   });
 
   afterEach(() => {
     localStorage.clear();
+    document.documentElement.lang = documentLanguage;
   });
 
   it('uses the stored language as the initial value', () => {