Thank you for playing my game, i'm glad you've been enjoying it so far!~
I'm testing encounters with Firion in my party using the build i'm currently working on (.27) and all his attacks seem to be working correctly for me.
It might be an issue with the currently updated version, or i'm not properly copying the conditions for the crash.
I'm not sure if the web version throws you error messages, but do you know if the game's music keeps going, or if it suddenly stops?
I'll continue to see if I can replicate it, but if you have any more details you could share about the crash, i'd greatly appreciate it ^v^