bug: keyboard catalog returning `[]` in some circumstances?

[mcdurdin]

I'm not sure the circumstances, but from the Sentry logs it appears there's times the Cloud catalog queries return [] and the Keyman Engine JSON parsing code throws an exception treating it as a JSONObject.

I think I'd like to verify the root cause of this on api.keyman.com as well -- and make sure that there are not circumstances where this is happening, wrongly.

Originally posted by @mcdurdin in keymanapp/keyman#7611 (comment)