Don't swallow errors in API code

[Nutomic]

I am currently trying to help the admin of forum.nogafam.es to debug a problem on the instance. The problem is that fetching remote communities or other objects doesnt work, and it only returns "error: couldnt_find_object". The actual error message from search_by_apub_id() is silently dropped, but it should be logged at the very least.

https://github.com/LemmyNet/lemmy/blob/main/crates/api/src/site.rs#L390

This same pattern is used all over the API code, and should be fixed everywhere.