I've just installed J51 Natalie and I'm getting a zero error message:

Cannot access protected property Joomla\CMS\Menu\MenuItem::$params
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0 Cannot access protected property Joomla\CMS\Menu\MenuItem::$params
/homepages/3/d648537963/htdocs/leonardclark_com/BraemarHouse/templates/j51_natalie/index.php:41

The call stack is:
1 () JROOT/templates/j51_natalie/index.php:41
2 require() JROOT/libraries/src/Document/HtmlDocument.php:731
3 Joomla\CMS\Document\HtmlDocument->_loadTemplate() JROOT/libraries/src/Document/HtmlDocument.php:785
4 Joomla\CMS\Document\HtmlDocument->_fetchTemplate() JROOT/libraries/src/Document/HtmlDocument.php:622
5 Joomla\CMS\Document\HtmlDocument->parse() JROOT/libraries/src/Application/CMSApplication.php:1057
6 Joomla\CMS\Application\CMSApplication->render() JROOT/libraries/src/Application/SiteApplication.php:732
7 Joomla\CMS\Application\SiteApplication->render() JROOT/libraries/src/Application/CMSApplication.php:311
8 Joomla\CMS\Application\CMSApplication->execute() JROOT/includes/app.php:58
9 require_once() JROOT/index.php:32

Any idea what I'm doing wrong?