Error template does not display search/nav markdown

[chilblane]

I've noticed that the error handling seems to only process error.status and error.message, and no longer handles processing the rest of the markdown for the template. This means for my project, the error template won't show our category UI or any placeholder text in the search box. Raneto's own error template displays this issue as well: http://docs.raneto.com/404

This is problematic for a 404 page, as for my project, navigation and search UI is critical on "Page Not Found."