I just tested out the game by downloading it from here on itch, but I didn't run into this error after the message. You were talking about the one right after the intro, right? I'm asking because you can also check how to play the game if you look in your items menu. So far after the intro, it seems fine.
Regardless, I fixed a few minor things in the game like spelling mistakes and stuff, so try downloading it now, maybe it'll work this time? I have a friend that has also played the game, and he doesn't seem to have run into any errors after the intro, so I honestly have no idea what it could be. I'm sorry if its still not working. :(