I'm gonna have to look into this more closely prior to Web-Release (so in the next month or so). I've got a couple of different machines (including a mac) that I can test on with different browsers. One thing it might be that others noticed was you have to have your local storage enabled or else it either won't run or pretty much stops working immediately.
Viewing post in Stuck at Loading 99% or Loading Complete?
I looked more closely at the error message that I was seeing in the console and saw that the error was coming from trying to parse JSON that was read from local storage. I tried clearing out cookies for itch.io (I think that includes clearing out local storage in Chrome?) and the game now loads in Chrome on my M1 Macbook Pro that previously had been stuck loading at 98 or 99%.
Perhaps some corrupted data got stored in local storage?