Oh, dear, we have a 0

xmap_com_acymailing::getTree(): Argument #2 ($parent) must be of type stdClass, Alledia\OSMap\Sitemap\Item given

Please try one of the following pages:

Call stack
# Function Location
1 () JROOT/plugins/xmap/com_acymailing/com_acymailing.php:36
2 xmap_com_acymailing::getTree()  
3 call_user_func_array() JROOT/administrator/components/com_osmap/library/Alledia/OSMap/Helper/General.php:394
4 Alledia\OSMap\Helper\General::callUserFunc() JROOT/administrator/components/com_osmap/library/Alledia/OSMap/Sitemap/Collector.php:554
5 Alledia\OSMap\Sitemap\Collector->callPluginsGetItemTree() JROOT/administrator/components/com_osmap/library/Alledia/OSMap/Sitemap/Collector.php:225
6 Alledia\OSMap\Sitemap\Collector->fetch() JROOT/administrator/components/com_osmap/library/Alledia/OSMap/Sitemap/Standard.php:148
7 Alledia\OSMap\Sitemap\Standard->traverse() JROOT/components/com_osmap/views/html/tmpl/default_items.php:38
8 include() JROOT/libraries/src/MVC/View/HtmlView.php:701
9 Joomla\CMS\MVC\View\HtmlView->loadTemplate() JROOT/components/com_osmap/views/html/tmpl/default.php:70
10 include() JROOT/libraries/src/MVC/View/HtmlView.php:701
11 Joomla\CMS\MVC\View\HtmlView->loadTemplate() JROOT/libraries/src/MVC/View/HtmlView.php:230
12 Joomla\CMS\MVC\View\HtmlView->display() JROOT/libraries/allediaframework/Framework/Joomla/AbstractView.php:87
13 Alledia\Framework\Joomla\AbstractView->display() JROOT/administrator/components/com_osmap/library/Alledia/OSMap/View/Site/AbstractList.php:143
14 Alledia\OSMap\View\Site\AbstractList->display() JROOT/libraries/src/MVC/Controller/BaseController.php:664
15 Joomla\CMS\MVC\Controller\BaseController->display() JROOT/libraries/src/MVC/Controller/BaseController.php:702
16 Joomla\CMS\MVC\Controller\BaseController->execute() JROOT/components/com_osmap/osmap.php:35
17 require_once() JROOT/libraries/src/Component/ComponentHelper.php:402
18 Joomla\CMS\Component\ComponentHelper::executeComponent() JROOT/libraries/src/Component/ComponentHelper.php:377
19 Joomla\CMS\Component\ComponentHelper::renderComponent() JROOT/libraries/src/Application/SiteApplication.php:194
20 Joomla\CMS\Application\SiteApplication->dispatch() JROOT/libraries/src/Application/SiteApplication.php:233
21 Joomla\CMS\Application\SiteApplication->doExecute() JROOT/libraries/src/Application/CMSApplication.php:225
22 Joomla\CMS\Application\CMSApplication->execute() JROOT/index.php:49