banned-players, banned-ips and ops json files are broken in 20w09a server

Trying to op a player though console results in an unknown error. Upon closer inspection, the ops json file is malformed and contains no data. Restarting and deleting it and retrying result in the same bug.

Oddly, while banning a player, the ban would not keep between restarts. I solved this by setting the Immutable file attribute on banned-players.json

The whitelist file seems fine.