query.c:8367: INSIST(qctx->rdataset == ((void *)0) || (((&qctx->client->query)->attributes & 0x40000) != 0)) failed

As reported in BIND 9.16.13-S1

18-Mar-2021 13:19:40.211 query.c:8367: INSIST(qctx->rdataset == ((void *)0) || (((&qctx->client->query)->attributes & 0x40000) != 0)) failed, back trace
18-Mar-2021 13:19:40.211 #0 0x55e22a736cf4 in ??
18-Mar-2021 13:19:40.211 #1 0x7f3df81838a0 in ??
18-Mar-2021 13:19:40.211 #2 0x7f3df9818af9 in ??
18-Mar-2021 13:19:40.211 #3 0x7f3df9818ca4 in ??
18-Mar-2021 13:19:40.211 #4 0x7f3df98131ec in ??
18-Mar-2021 13:19:40.211 #5 0x7f3df9819511 in ??
18-Mar-2021 13:19:40.211 #6 0x7f3df98199aa in ??
18-Mar-2021 13:19:40.211 #7 0x7f3df81ba11b in ??
18-Mar-2021 13:19:40.211 #8 0x7f3df81c0636 in ??
18-Mar-2021 13:19:40.211 #9 0x7f3df65f315a in ??
18-Mar-2021 13:19:40.211 #10 0x7f3df6324f73 in ??
18-Mar-2021 13:19:40.211 exiting (due to assertion failure)

ISC packaged RPM for RHEL/Centos 8 etc..

Originally occurred with these serve-stale settings:

	stale-answer-enable yes;
//	stale-answer-client-timeout 0;
	max-stale-ttl 1w;

Uncommenting stale-answer-client-timeout 0; appears to prevent the crashes, otherwise they're occurring very frequently.