Hi! I'm so sorry that you've experienced this :((
These are two bugs that we've been trying to fix for a while after we submitted it. Thankfully, we've found that downloading the game or playing on a different browser (like microsoft edge) should fix the crashing. I hope this fixes the crashing! As for the invincible enemies, we will continue to look into it. Thank you for playing our game, and I'm glad you liked the art!!