postgREST current behavior is to do a
LIMIT 1 OFFSET 0 when doing a GET with
plurality=singular, I think it will be more appropriate to give an error when more than one row would be returned.
This would help with client errors, for example a while back I got a case of a duplicate key and postgREST could have helped me there since I mostly use
plurality=singular when explicitly requesting a single row with filters or a limit.
Also this would be a more consistent behavior since POST and PATCH already give an error when returning more than one mutated row.