hey, really cool - I experienced no bugs, collisions seems to be working fine, the mechanics for double jumping work as I would expect them to, overall everything seems to be solid.
If I had to list some issues, I'd say that it would be great to add some more depth to the mechanics. Perhaps ducking to dodge projectiles from enemies and blocking melee attacks with your sword would be a good start? Enemies in the game telegraph their attacks slightly, so I would expect some way to capitalize on that and dodge or block quickly when I spot an attack is coming.
Also I think it would be cool if apples were more sparse but dealt more damage :) It's the "Apple Knight" after all, so it would make sense for apples to be a sort of a special attack.