So I got the exact same error when making my game, what fixed it for me was downgrading emscripten (to 6.0.0). While I can't rate it properly because it doesn't work, I will build it for my own system, try it out, and give my thoughts on it :)
Update: THIS GAME IS SO COOL!! It's such a shame the web build doesn't work... It was a little confusing at first, so I would add a tutorial, and also there's no indicator for if your troops have moved on the current round or not. Amazing work!
