Arrrgh!

Very briefly got out SVG output for a NUBS curve yesterday. Tried to make it a bit nicer looking, and had it promptly dissolve in a hail of bus errors. (And occasional "too many positional arguments: 3 passed, 1 expected" errors that I think must be incorrect.) It's now reminding me of my attempt to write an Euclidean geometry proof generator in Lisp back in '92 -- seemingly minor, innocent changes in the code lead to crazy changes in where it crashes.

Anyone have hints for how to approach debugging this sort of thing in Rakudo? I know it's just part of the frustration expected for an early Perl 6 adopter, but I'd really like to get this thing working...