Yesterday we were getting an emails from our users that the Studio that shipped with the last stable build (#499) throwing exceptions.
This problem has been fixed in this build (531).
This fix is the only change in this build, so you can safely upgrade any #499 build instances to that one.
Regards the new studio and some other features that exist in the unstable build, they will be included in the next stable build, which we plan to publish in the next week.