Altering leaderboard columns breaks a live contest. No additional saves can be made

I was working with Ihsan and we made changes to the leaderboard columns. Specifically removing the columns. Everthing seemed to work properly but not I can't make any changes to the site. Trying to save any changes, even small, results in the following console error.

Live contest: https://www.codabench.org/competitions/edit/3888/#/pages