I think it's a problem with the emulator you're using because the game is designed for computers, and it doesn't cause any problems on Windows.
Agree, going by the stack dump that's definitely Joiplay doing something.
That line in rpg_scenes.js is about triggering the zoom/wipe effect before a battle, which is what the JoiMV.js is handling (and I have no access to). Have you tried starting over and getting into any battles in the first forest screen before trying to catch the bunny? Because there's nothing special about starting the boss battle except setting the music. It's even going to use the same background as a random Bug encounter on the first forest screen.
I would ask about this on the Joiplay Discord or Reddit.