When a Required Thing is missing, it displays as the cryptic "Some HTML" link

(Bug, Closed -> Fixed, Priority: Critical, Test Status: No automated tests yet , Reported By Justin du Coeur, )
UX
Summary: This is technically correct, but makes no sense to the end user. Fix it.
The problem is that, due to the way the pipeline works, if the Thing is missing it winds up displaying as an empty value of RawHtmlType, which is internally named "Some HTML". That's why this kind of makes sense from a code perspective. But that's mostly irrelevant: since it is occasionally user-visible, it needs to display in a way that is actually helpful to the user.
So I'm renaming this to "Required Property has not been set", and I'm giving it a Default View so that, if you click on it, you get a decently helpful error message.