It even breaks Deparse.pm:

[jeffa@trinity perl]$ perl -MO=Deparse wc.pl
Can't call method "sibling" on an undefined value at Deparse.pm line 257.
CHECK failed--call queue aborted.

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)