After the game is completed, it was my intention to have it conduct a fresh "restart" so a new game could be played right away without any issues... I'm not entirely sure why I thought this was necessary, it just seemed like the right thing to do.
Unfortunately this appears to generate an error on MacOS and causes a crash, so I have removed this action from the game.
If (for some reason) players do want to start a new game right away after completing, simply close the game and restart it manually.
Tom