I'm not sure if I am not using properly but the issue I'm facing is having the trailing comma option set to all adds it to JSON entries as well. This is causing syntax errors and I have to disable prettier to edit JSON files unless I turn of trailing commas.

This was discovered in VSCode prettier extension so could be an issue there and not here, just thought I would bring it to your attention! If this does end up being an issue it looks interesting and if given some direction I would gladly take a look and open a PR to fix!