Hey so the update you did worked and I'm able to play the game now!
Anyways, I like your implementation of the theme and special object. The gameplay loop is fun too, and reminds me of those old sidescrolling beat-em-up games. The sprites and music are also good!
My main concern is that sometimes my character would freeze? Like, sometimes after shooting notes the character would straight up become frozen and I wouldn't be able to move or shoot notes. Enemies wouldn't be able to attack me in this frozen state either, as they would just walk up to me but not play their attack animation. Another minor thing is that it took me a while to figure out that "z" is how you shoot. I was pressing spacebar, trying to click my mouse, and pressed a bunch of other keys, so maybe a short tutorial blurb would be good.
Overall, I had fun! Just some polish needed but the main gameplay loop is there.