Inconsistent response of sort as a result of indexing of a predicate

It makes mathematical sense. But in a real world scenario, sure why not? Then we can have this sort of things for a random number generator:

_:a <name> "foo".
_:a <rnd> NaN. 
_:b <name> "bar".
_:b <rnd> NaN.
_:c <name> "baz".
_:c <rnd> NaN.

or this type of query for random sorts:

q(func: has(name), orderasc: nonexistantPredicate, first:1) {
...
}

How exciting.

EDIT: tried the latter query (added a “nonsense” predicate first). Got empty results when indexed, but a static, non-random result when index is removed. Hmm. This seems like a bug