If you got the "OOPS" screen then it mean that they died.I tried it just to check if i got the issue also but I never did and it proceeded as normal,unfortunately I'm unsure what the problem could be :(You can pause with P and go back to menu in case you got stuck,the game saves your progress.
Also before you reload the page,make sure you QUIT the game,so when it reloads the page your progress should still be there