FRX removal might cause intermittent error messages

After patch has been removed its FRXs still present in the review page.
Crucible does some background work (e.g. loads FRXs) that cannot be completed because an info about the patch was removed from the server.
Also system shows an error when user tries to see FRX by clicking it in files tree.

The issue found in 3.9.0, but seems like it's an old one.

Workaround is to refresh the page.