WIP: Highlights "+ Add Criterion" when 0 criteria and author tries to save

TWO things which still have to be done:
1) When we don't have a criterion prompt, we need to highlight that too
2) A suitable test case for this. 
The purpose of this function is to report what errors are actually being displayed in the UI (for testing purposes).  So I think you want to check whether the add button is highlighted, not whether the criteria length is 0.