After much testing with various versions of byond. I've come to the conclusion that this bug is somehow related to the game coding and not the latest byond update.
Sadly Eviler won't be home until the 14th and won't be able to fix this. The only current work around for the crashing is to click the player tab and turn SFX off.
We'll have this bug fixed soon enough, just can't play with our awesome SFX </3