_output was missing I rebuilt the add-on, but it did not fix the issue.
Here is the stack trace:
#0 [internal function]: XF\Template\Templater->handleTemplateError(512, '[E_USER_WARNING...', '/srv/www/forums...', 1277)
#1 src/XF/Template/Templater.php(1277): trigger_error('Method canViewW...'...