remove default "any" condition; return error if you attempt to release an assignment w no labels?

[Kim Jones Davenport]

When an instructor attempts to release an assignment w no labels, OST applies the "any" presentation and feedback conditions. Should we remove the default "any" conditions and instead return an error if an assignment has no labels? It would prevent educators from sending out an assignment under conditions they might not want (or be aware of).

Also, the default basic feedback condition doesn't totally make sense; AvailabilityEvent is not set, so feedback never becomes available, but the feedback credit is set to 0 for some reason. We could change it, but @kevinburleigh75 pointed out this might have backwards-compatible consequences.