If I query for the items on a schedule and specify an empty group (e.g. mastery_9, for a schedule where I haven't mastered any terms), instead of a JSON response with an empty terms array, I get an HTML page with the following message:
We're terribly sorry, but an error has occurred on the site. An error report has automatically been sent.
Huh, I actually can't replicate the bug this morning either. I made exactly the same API call (api.renshuu.org/v1/schedule/7756897/list?pg=1&group=mastery_9), and this time I see the empty terms list just like your example. Thanks for checking!
