plperl error format vs plpgsql error format vs pgTAP

I use pgTAP to make sure my functions produce the correct errors using
throws_ok().  So when I get an error from a plpgsql function, it looks
like this:

ERROR:  upper bound of FOR loop cannot be null
CONTEXT:  PL/pgSQL function "foo" line 35 at FOR with integer loop
variable

...which I can then test using throws_ok by giving it the string
'upper bound of FOR loop cannot be null'.  However, in a plperl
function, errors come out in this format:

error from Perl function "check_no_loop": Loops not allowed!  Node 1
cannot be part of node 3 at line 13.

Unfortunately, I can't test for this without including the line
number, which means that changing any plperl function that I have such
a test for pretty much guarantees that I'll need to change the test to
reflect the new line numbers the errors would be thrown from in the
function.

Is it possible to unify the error reporting format, so pgTAP can test
them without needing line numbers from plperl functions?