Uncaught TypeError: Cannot read property 'onMessage' of null at line 1925 of SupRuntime.js. OS X El Capitan 10.11.6, Electron 1.3.4. The game runs fine when launched from the IDE; this issue only happens on exported versions.
It looks like Superpowers' code is contradicting itself. Here you work around SupApp not existing, but a few lines later you just assume it exists, without having done anything to set it in the meantime.
I'd do more to help, but I can't for the life of me figure out what SupApp actually is, or how to replace onMessage with (presumably) something from Electron.
(Crossposted from an issue I opened on GitHub.)