If a non-admin visits https://en.wikipedia.org/w/index.php?title=Topic:S1u4yp09cwg7ku3l (a deleted topic)
they receive this error message:
Insufficient permission to access the content.
Return to Main Page.
[6138f9cc] 2014-09-06 19:39:49: Fatal exception of type Flow\Exception\PermissionException
There should be a more informative message for readers, so that they can understand what happened. The standard is a message like this: https://en.wikipedia.org/w/index.php?title=Talk:Gabriel_de_Saint_Nicholas&redirect=no