Hi, great alpha release! I'm impressed by what you've already gotten into the game. Two crashes I hope I can help you narrow down and squish.
1. Throwing javelin when thrown the majority of times causes a crash. The only time it didn't seem to crash is when the attack didn't connect, still being able to pick up the javelin afterwards.
2. Use of Chain Lightning. The ability seems like it goes off without a hitch, then about when it is (almost?) resolved the game crashes. I didn't see any of the "Chain" part of the lightning occur, maybe it has something to do with that? First time it crashed when I targeted an enemy, the second time I just targeted the ground and it still occurred.
Hope this helps! Looking forward to seeing the evolution of this project.