Fix the build (#2400)

* Fix the UID bug.
* If we find a deleted version, stop iteration.
* Rename dummyPostingList to emptyPostingList, which is what it is.
* Instead of adding a dummy key, remove a dummy key, so dummy predicate doesn't show up in our states.
* Use require for testing, instead of assert.
* Be able to pick up Facets as well, via json.Number.