All errors of SQLSTATE class 23 should include the name of an object
associated with the error in separate fields of the error report message.
We do this so that applications need not try to extract them from the
possibly-localized human-readable text of the message.

Reported-by: Chris Bandy
Author: Chris Bandy
Reviewed-by: Amit Kapila and Amit Langote
Discussion: https://postgr.es/m/0aa113a3-3c7f-db48-bcd8-f9290b2269ae@gmail.com