executed in an implicitely aborted transaction (e.g. after an occur
occurs), we return an error (and not just a warning). For example:

nconway=# begin;
BEGIN
nconway=# insert; -- syntax error
ERROR:  parser: parse error at or near ";"
nconway=# select * from a;
ERROR:  current transaction is aborted, queries ignored until end of
transaction block

The old behavior was:

nconway=# begin;
BEGIN
nconway=# insert;
ERROR:  parser: parse error at or near ";"
nconway=# select * from a;
WARNING:  current transaction is aborted, queries ignored until end
of transaction block
*ABORT STATE*

Which can be confusing: if the client isn't paying careful attention,
they will conclude that the query has executed (because no error is
returned).

Neil Conway