Re: [PATCH 3/6] connected: refactor iterator to return next object ID directly

> The object ID iterator used by the connectivity checks returns the next
> object ID via an out-parameter and then uses a return code to indicate
> whether an item was found. This is a bit roundabout: instead of a
> separate error code, we can just retrun the next object ID directly and
> use `NULL` pointers as indicator that the iterator got no items left.
> Furthermore, this avoids a copy of the object ID.
> 
> Refactor the iterator and all its implementations to return object IDs
> directly. While I was honestly hoping for a small speedup given that we
> can now avoid a copy, both versions perform the same. Still, the end
> result is easier to understand and thus it makes sense to keep this
> refactoring regardless.