CoreTermSearchFacetResult.terms() returns null if field is absent from all documents

Suggested Release Note:

Accessing the terms of a `TermFacet` result no longer throws NullPointerException if the target field is absent from all documents.

In Java, this surfaces as a NullPointerException when calling `TermSearchFacetResult.terms()`, as in this reproducer:

It's worse in Kotlin, where the results are converted eagerly; Kotlin gets an NPE inside `searchQuery`, before the user even touches the facet results.