So, I wasn't able to play the game on the web, though I could download the HTML file itself and play that. The error message makes me think you may have not indicated to itch properly that this was an HTML?
Underneath the "Kind of Project" dropdown, you have to select "HTML" (this won't override any local desktop builds, so don't worry about that), and then underneath your uploaded files, there should be a checkbox saying "This file will be played in the browser".
Anyway, it is quite janky but, you know, I couldn't even finish most of my first projects, so you're doing way better than I was when starting out. The biggest issue for me is that some of the buttons don't do anything. But, however imperfect, it's always a success just being able to get a game finished. So, nicely done!