Steps to reproduce:

1. Open Zabbix Web UI
2. Expand Monitoring
3. Click on Problems (without any filters applied)

Result:
[php:error] [pid 562821] [client *.*.*.*:26666] PHP Fatal error:  Uncaught TypeError: count(): Argument #1 ($value) must be of type Countable|array, bool given in /usr/share/zabbix/include/classes/screens/CScreenProblem.php:286\nStack trace:\n#0 /usr/share/zabbix/include/classes/screens/CScreenProblem.php(824): CScreenProblem::getData()\n#1 /usr/share/zabbix/app/partials/monitoring.problem.view.html.php(73): CScreenProblem->get()\n#2 /usr/share/zabbix/include/classes/mvc/CPartial.php(104): include('...')\n#3 /usr/share/zabbix/include/classes/html/CObject.php(81): CPartial->getOutput()\n#4 /usr/share/zabbix/include/classes/html/CObject.php(61): unpack_object()\n#5 /usr/share/zabbix/include/classes/html/CTag.php(90): CObject->addItem()\n#6 /usr/share/zabbix/include/classes/html/CObject.php(68): CTag->addItem()\n#7 /usr/share/zabbix/include/classes/html/CTag.php(90): CObject->addItem()\n#8 /usr/share/zabbix/include/classes/html/CObject.php(68): CTag->addItem()\n#9 /usr/share/zabbix/include/classes/html/CTag.php(90): CObject->addItem()\n#10 /usr/share/zabbix/include/classes/html/CTag.php(47): CTag->addItem()\n#11 /usr/share/zabbix/include/classes/html/CHtmlPage.php(131): CTag->__construct()\n#12 /usr/share/zabbix/include/classes/html/CHtmlPage.php(98): CHtmlPage->toString()\n#13 /usr/share/zabbix/app/views/monitoring.problem.view.php(77): CHtmlPage->show()\n#14 /usr/share/zabbix/include/classes/mvc/CView.php(128): include('...')\n#15 /usr/share/zabbix/include/classes/core/ZBase.php(721): CView->getOutput()\n#16 /usr/share/zabbix/include/classes/core/ZBase.php(645): ZBase->processResponseFinal()\n#17 /usr/share/zabbix/include/classes/core/ZBase.php(228): ZBase->processRequest()\n#18 /usr/share/zabbix/include/config.inc.php(20): ZBase->run()\n#19 /usr/share/zabbix/zabbix.php(17): require_once('...')\n#20 {main}\n  thrown in /usr/share/zabbix/include/classes/screens/CScreenProblem.php on line 286
[Tue Jun 18 06:57:06.467750 2024] [php:warn] [pid 562821] [client *.*.*.*:26666] PHP Warning:  Undefined array key "file" in /usr/share/zabbix/include/classes/debug/CProfiler.php on line 376
[Tue Jun 18 06:57:06.467771 2024] [php:warn] [pid 562821] [client *.*.*.*:26666] PHP Warning:  Undefined array key "line" in /usr/share/zabbix/include/classes/debug/CProfiler.php on line 376
[Tue Jun 18 06:57:06.467784 2024] [php:warn] [pid 562821] [client *.*.*.*:26666] PHP Warning:  Cannot modify header information - headers already sent in /usr/share/zabbix/include/classes/helpers/CCookieHelper.php on line 54
[Tue Jun 18 06:57:06.467797 2024] [php:warn] [pid 562821] [client *.*.*.*:26666] PHP Warning:  Unknown: Failed to write session data using user defined save handler. (session.save_path: /var/lib/php/sessions) in Unknown on line 0
Expected:
The problem view to open up and display any problems that it might have retrieved.

Observations:

CScreenProblem.php
$problems = ($filter['show'] == TRIGGERS_OPTION_ALL)
        ? self::getDataEvents($options)
        : self::getDataProblems($options);
$end_of_data = (count($problems) < $limit + 1);
$problems seems to be returning a boolean instead of an array when getDataProblems is called.