Simplify code at a few places

Remove some duplicate checks,
and unnecessary errors.
> I am not even sure when we have this situation.

`setupAnnotation` is called for annotations that are loaded, too, not just ones that are created.
If they are replies, the only reason they have a target property is because we're setting it here.

I think we have the proper guards everywhere in the h codebase. We should just skip the for loop here if there are no targets.