resolver.c:10470 assertion fail causes bind to die

Summary

critical: resolver.c:10470: REQUIRE(fetchp != ((void *)0) && *fetchp == ((void *)0)) failed, back trace assertion doesn't explain what's expected rather than a null pointer.

BIND version used

9.13.4+, doesn't happen in 9.13.3

Steps to reproduce

unknown, sometimes triggers within minutes, sometimes within days. rebuilding with debug enabled to generate usable back trace

What is the current bug behavior?

named crashes

What is the expected correct behavior?

named reports an error and keeps running

Relevant configuration files

named.conf hasn't changed in years and it works with 9.13.3.

┌[✓ root@Scott [~]
└─> named-checkconf -px
acl "xfer" {
	"none";
};
acl "trusted" {
	10.0.0.0/24;
	10.69.0.0/24;
	10.69.1.0/24;
	10.99.0.0/24;
	127.0.0.0/8;
	173.12.76.128/29;
	192.168.43.0/24;
	::1/128;
};
controls {
	inet 127.0.0.1 port 953 allow {
		127.0.0.1/32;
		::1/128;
	} keys {
		"rndc-key";
	};
};
logging {
	channel "default_log" {
		file "/var/log/named/named.log" versions 5 size 52428800;
		severity info;
		print-time yes;
		print-severity yes;
		print-category yes;
	};
	category "default" {
		"default_log";
	};
	category "general" {
		"default_log";
	};
	category "xfer-in" {
		"default_log";
	};
	category "xfer-out" {
		"default_log";
	};
	category "notify" {
		"default_log";
	};
};
options {
	directory "/var/named";
	listen-on {
		127.0.0.1/32;
		10.0.0.1/32;
	};
	listen-on-v6 {
		::1/128;
	};
	pid-file "/run/named/named.pid";
	allow-query-cache {
		"trusted";
	};
	allow-recursion {
		"trusted";
	};
	dnssec-enable yes;
	dnssec-validation auto;
	allow-query {
		"trusted";
	};
	allow-transfer {
		"none";
	};
	allow-update {
		"none";
	};
	forwarders {
		10.69.0.2;
		10.69.0.3;
		4.2.2.1;
		4.2.2.2;
		8.8.8.8;
		8.8.4.4;
	};
};
key "rndc-key" {
	algorithm "hmac-md5";
	secret "????????????????????????????????????????????";
};
zone "." in {
	type hint;
	file "/var/named/root.hint";
};
zone "localhost" IN {
	type master;
	file "localhost.zone";
	notify no;
};
zone "127.in-addr.arpa" IN {
	type master;
	file "127.0.0.zone";
	notify no;
};

Relevant logs and/or screenshots

the only currently relevant line is pasted above

Possible fixes

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