How does the 404 page you can define in /admin/config/system/site-information work?
I found Drupal\system\Controller\Http4xxController->on404(), but how does that display whatever path I definied in basic site settings?
I'm trying to deliver a 410 when a page is deleted. I hve a database table with deleted paths, an InboundPathProcessorInterface to call a custom controller. Now I want to output the exact same thing as a 404, just with another status code.
Alternativly, how do I get the content of a given system path (i.e. node/123) to output in a Symfony\Component\HttpFoundation\Response?