Steps to reproduce:

1. Click to Alerts -> Actions -> Trigger actions.

Result:
Frontend HTTP 500 error:

[php:error] [pid 962652:tid 962652] [client 91.206.16.254:52670] PHP Fatal error:  Uncaught TypeError: array_key_exists(): Argument #2 ($array) must be of type array, bool given in /usr/share/zabbix/include/actions.inc.php:277\nStack trace:\n#0 /usr/share/zabbix/app/controllers/CControllerActionList.php(143): actionConditionValueToString()\n#1 /usr/share/zabbix/include/classes/mvc/CController.php(473): CControllerActionList->doAction()\n#2 /usr/share/zabbix/include/classes/core/ZBase.php(642): CController->run()\n#3 /usr/share/zabbix/include/classes/core/ZBase.php(228): ZBase->processRequest()\n#4 /usr/share/zabbix/include/config.inc.php(20): ZBase->run()\n#5 /usr/share/zabbix/zabbix.php(17): require_once('...')\n#6 {main}\n  thrown in /usr/share/zabbix/include/actions.inc.php on line 277, referer: https://xxxxxxxx.xxx/zabbix/zabbix.php?action=user.list
Expected:
No errors.