Assert the hevent->rdataset is non-NULL.

5709			    NEGATIVE(hevent->rdataset)) {
32
←
Within the expansion of the macro 'NEGATIVE':
a
Access to field 'attributes' results in a dereference of a null pointer (loaded from field 'rdataset')

5710				INSIST(eresult == DNS_R_NCACHENXDOMAIN ||
5711				       eresult == DNS_R_NCACHENXRRSET);
5712			}