Recreating steps:
Just open https://meta.discourse.org in “incognito” web-browser session.
And press “G” then “N” from your keyboard. (goes to /new).
Result:
Checked here, and at sandbox site (http://try.discourse.org/new).
Regards!
Ps, I’m not sure if this is a real “bug”. 
not a bug, methinks. if you are not logged in then the new page has no purpose. but maybe the error could be friendlier. 
Hmm yeah we should not show an error in this case though. cc: @eviltrout if it is an easy fix go for it
Added support for anonymous keyboard shortcuts:
https://github.com/discourse/discourse/commit/9548876c2d6b5b14fe42c4fb4f5376ae293c880b
