Awesome game (Made in Godot, right?). I am not gonna repeat what everyone said but instead give you a doable solution for the error at the end. You can add a Main Scene node out of the Scenes Folder (If you have one), and instance the game inside it. Move the music player node into that main scene and trigger the playing property of the player through the same. This won't cause that loop thing to happen.
I made this kind of error in my last game jam (first time in Godot), which caused my music loop to reset every time the game went into the restart state. I changed that in my entry in this jam.
Hope this helps! Cheers! Enjoyed playing your game !