Same problem with T3 framework update from 3.0.4 to 3.0.5 and running Purity III 2.0.1.
Joomla version is 3.10.2.
0 - Call to a member function get() on null
Call to a member function get() on null
Call stack
# Function Location
1 () JROOT/plugins/system/t3/includes/menu/t3bootstrap.tpl.php:31
2 T3BootstrapTpl::render() JROOT/plugins/system/t3/includes/menu/t3bootstrap.php:44
3 T3Bootstrap->render() JROOT/plugins/system/t3/includes/renderer/t3bootstrap.php:42
4 JDocumentRendererT3Bootstrap->render() JROOT/libraries/src/Document/HtmlDocument.php:501
5 Joomla\CMS\Document\HtmlDocument->getBuffer() JROOT/libraries/src/Document/HtmlDocument.php:793
6 Joomla\CMS\Document\HtmlDocument->_renderTemplate() JROOT/libraries/src/Document/HtmlDocument.php:567
7 Joomla\CMS\Document\HtmlDocument->render() JROOT/libraries/src/Application/CMSApplication.php:1140
8 Joomla\CMS\Application\CMSApplication->render() JROOT/libraries/src/Application/SiteApplication.php:778
9 Joomla\CMS\Application\SiteApplication->render() JROOT/libraries/src/Application/CMSApplication.php:231
10 Joomla\CMS\Application\CMSApplication->execute() JROOT/index.php:49
Thanks