editors view of papers when not logged in to JOSS

[danielskatz]

When I'm not logged into JOSS and try to see a paper in the JOSS system, eg. https://joss.theoj.org/papers/{hash}, I get a blank page rather than an error. I've now mostly trained myself to remember that this means I need to login JOSS and reload the page, but it would be nice if there was an error page that told me this, and perhaps pointed me to the login page