Would probably make more sense if it returned something other than 500.
In my logs I got
ActionView::Template::Error (Discourse::InvalidAccess)
/var/www/discourse/lib/auth/default_current_user_provider.rb:79:in `current_user'
「いいね！」 1
Added on my list to look into. 
「いいね！」 5
Improved error message via:
「いいね！」 4