Isn't normal..
First question : are you using mods?
Second question : you modified in any way the HTML or save file?
there is mods? I would say no. Even if I did I restarted the game several times on different browsers still same issue.
When you modify the HTML code no matter how many different browser you will use, you will get always the same error if you didn't coded right..
Just download/extract the game, i bet the error will disappear..
deleted, downloaded it, extracted, ran the game same issue
Out of suggestions.. Unless you modified some variables that shouldn't happens..
You choose perhaps a Custom Gender at start?
Report it with a save game on Discord