Uncaught TypeError: Cannot access offset of type string on string

[devin]

[15-Mar-2023 17:44:36 Etc/UTC] PHP Fatal error:  Uncaught TypeError: Cannot access offset of type string on string in /etc/inc/system.inc:422
Stack trace:
#0 /etc/inc/system.inc(520): system_hosts_dhcpd_entries()
#1 /etc/inc/system.inc(551): system_hosts_entries(Array)
#2 /etc/rc.bootup(195): system_hosts_generate()
#3 {main}
  thrown in /etc/inc/system.inc on line 422
[15-Mar-2023 17:44:39 Etc/UTC] PHP Fatal error:  Uncaught TypeError: Cannot access offset of type string on string in /etc/inc/system.inc:422
Stack trace:
#0 /etc/inc/system.inc(520): system_hosts_dhcpd_entries()
#1 /etc/inc/system.inc(551): system_hosts_entries(Array)
#2 /etc/inc/services.inc(2772): system_hosts_generate()
#3 /usr/local/pkg/wireguard/includes/wg_service.inc(322): services_unbound_configure()
#4 /usr/local/pkg/wireguard/includes/wg_service.inc(303): wg_restart_extra_services()
#5 /usr/local/pkg/wireguard/includes/wg_service.inc(60): wg_service_cli_start(false)
#6 {main}
  thrown in /etc/inc/system.inc on line 422

This error occurred during an upgrade from 22.05 to 23.01. This error prevents all interfaces from coming up and router is completely unusable. Was able to repair from the console by editing the config.xml file. Empty entries created by the UI under <dhcpd> and <dhcpdv6> are incompatible with 23.01 code. Remove any empty tags manually from /config/config.xml and reboot and problem is gone

[jimp]

https://redmine.pfsense.org/issues/13983