After you kill the sixth enemy, there is a slightly tall wall. If you walk up to it and fire the fireball inside of the wall, the fireball will spin for awhile, stop, game will slowdown and then freeze in the browser. Not sure if this happens outside of firefox.
Viewing post in BornCG's Godot Tutorial Platformer! comments
You're correct! Tutorial Part #19 (Shooting Bouncing Fireballs) of this series is now up. The easy way to solve this: 'spawn' fireballs closer to the character, so that they aren't spawned inside the wall to start. Better: use a RayCast2D to stop Steve from even shooting a fireball if he's right next to, facing a wall.