The 'x' parameter (undef) to Y::foo was an 'undef', which is not one of the allowed types: scalar
 at Y.pm line 70.
	...
	ModPerl::ROOT::ModPerl::Registry::z_2ecgi::handler('Apache2::RequestRec=SCALAR(0xb61b6a8)') called at ...
	eval {...} called at ...
	ModPerl::RegistryCooker::run('ModPerl::Registry=HASH(0xb6360c8)') called at ...
	ModPerl::RegistryCooker::default_handler('ModPerl::Registry=HASH(0xb6360c8)') called at ...
	ModPerl::Registry::handler('ModPerl::Registry', 'Apache2::RequestRec=SCALAR(0xb61b6a8)') called at -e line 0
	eval {...} called at -e line 0