retrieveUserByIdOrNull
Retrieves a User with the provided ID.
Throws the same exceptions as JDA.retrieveUserById, minus ErrorResponse.UNKNOWN_USER.
Parameters
userId
ID of the user to retrieve
useCache
Whether this should rely on the cache, set to false
to always make a request.
See also
Same as ShardManager.retrieveUserById, but returns null
on ErrorResponse.UNKNOWN_USER.