How to response to non-processable tRPC requests

[smolak]

Scenario:
I want to like the userUrl entry. I check if the entry exists. It does not.

1. Do I respond with status: 'notFound' (or alike)?
2. Do I throw TRPCError with BAD_REQUEST code?

First one requires if check in the response.
2nd one can be caught using onError handler (need to try it, haven't used it like that).