Neither
public constructor(private readonly objectEntityService: ObjectEntityService) {}
nor
public constructor(entityServices: EntityServices) { entityServices.getEntityCollectionService("Object"); }
works inside a service. Injecting to a component works fine. The app compiles but I get a blank web page when it's served. Tested on Angular 11.0.6 and 11.2.3.
Edit: Creating a new blank service and injecting to it works. Injecting the entity service to a component and storing it inside the service with the injection issue through a method also works fine even though injecting it directly doesn't.