cmounce c58658f0b5 Use NonZero type to represent board edge exits ...

These are the only board indexes in the ZZT file format that cannot
reference the title screen; 0 is reserved to mean "no connection".
This change encodes that in the type system.

2026-01-28 14:57:32 -08:00

..

zzt

Use NonZero type to represent board edge exits

2026-01-28 14:57:32 -08:00