Minor point of custom taxonomies

Hi, thanks for your plugin, looks very useful. Just a minor point which would have saved me some time, is that custom taxonomies need to have show_in_rest for your settings page to work. Whilst that is understandable, it would have been nice to have had an alert to that effect on 401 ( or other ) failed returns. As a dev I could inspect the console and work out what was going on but not everyone is as technical.