So sayeth the docs for the get_*_hll global opcodes:
If the global doesn't exist, $1 is set to null.
However, the current implementation throws an exception if the global
doesn't exist instead of returning null. It was decided in
#parrotsketch on 15 Aug 2006 that returning null is the right thing
to do.
This is a fairly substantial change, requiring changes to tests and
compilers.
--
Matt Diephouse