Can I let PostgreSQL report the offending rows when a multi-row INSERT fails?
When inserting multiple rows


Not sure what exactly you mean. It should already report the content of the offending rows.

# CREATE TABLE foo ( x int );
-- Two rows that work.
# INSERT INTO foo VALUES (1), (2);
INSERT 0 2
-- Three rows that explode.
# INSERT INTO foo VALUES (1), (2), ('a');
ERROR:  invalid input syntax for integer: "a"
LINE 1: INSERT INTO foo VALUES (1), (2), ('a');
                                          ^


What more content are you looking for?