[Bot Issue] fcregister with an FC already registered causes key error

[lifehackerhansol]

Issue Description

The code seems to suggest that one may have both a 3DS and a Switch friend code, but this is not the case; adding a Switch FC after 3DS results in:

kurisu-kurisu-1  | asyncpg.exceptions.UniqueViolationError: duplicate key value violates unique constraint "friendcodes_pkey"
kurisu-kurisu-1  | DETAIL:  Key (user_id)=(<UID>) already exists.

This error is ignored entirely by the bot and sends a message that the second FC has been added when it has not in fact been added, which is further proven when fcquery is called and only one FC is returned.