Fatal error: Uncaught Error: Call to a member function getStoreIds() on null in /var/www/virtual/bagstar.pl/htdocs/vendor/mageplaza/magento-2-blog-extension/Block/Adminhtml/Category/Tree.php:159 Stack trace: #0 /var/www/virtual/bagstar.pl/htdocs/vendor/magento/module-catalog/Block/Adminhtml/Category/Tree.php(301): Mageplaza\Blog\Block\Adminhtml\Category\Tree->_getNodeJson(NULL) #1 /var/www/virtual/bagstar.pl/htdocs/vendor/mageplaza/magento-2-blog-extension/Block/Adminhtml/Category/Tree.php(139): Magento\Catalog\Block\Adminhtml\Category\Tree->getTree(NULL) #2 /var/www/virtual/bagstar.pl/htdocs/vendor/mageplaza/magento-2-blog-extension/Block/Category/Widget.php(44): Mageplaza\Blog\Block\Adminhtml\Category\Tree->getTree(NULL, '1') #3 /var/www/virtual/bagstar.pl/htdocs/app/design/frontend/RedInGo/Bagstar/Mageplaza_Blog/templates/category/widget.phtml(22): Mageplaza\Blog\Block\Category\Widget->getTree() #4 /var/www/virtual/bagstar.pl/htdocs/vendor/magento/framework/View/TemplateEngine/Php.php(59): include('/var/www/virtua...') in /var/www/virtual/bagstar.pl/htdocs/vendor/mageplaza/magento-2-blog-extension/Block/Adminhtml/Category/Tree.php on line 159