Everyone who has the game does not restart or pops the error "An error occurred running the Unity content on this page,...", here's a solution:
Problem is in cache of browser. Your browser doesn't load new data.
1) You have to signup in settings window (must have to do it FIRST)
1.1) Now you are having login for your save
1.2) Open game from incognito and try login (if you fail, contact with us, stop here, that means don't do 1.3 points)
1.3) Clean up cache of your browser (or you can just use incognito) ⚠️DONT DO IT WITHOUT SIGNUP⚠️
1.4) Continue play 🔥 (c)