If I try to look at a Space I can't read, I hang on "Loading..."

Summary: Encountered by Roza -- part one of a two-part bug, I believe.

Say I have a Space whose root URL is https://www.querki.net/u/justin/thingy/#!thingy. It is only readable by Justin. Joe tries to go to that URL, and he mysteriously finds himself hung at the "Loading..." screen, with the URL redirected to https://www.querki.net/#!thingy.

What's going on here is that the server is saying, "That Space doesn't exist, or you don't have read access to it", and is trying to redirect back to Index. Problem is, the "#!thingy" part lives in the browser, so it's being reattached to the URL after the redirect. And since there is a ThingId in the URL, it's trying to load that Thing's Page, despite not actually being in a Space.