If domain was just removed, it the qrexec call may result in a
QubesVMNotFoundError exception. If it was removed earlier, and the
caller is in connecting via qrexec, the call will be rejected at the
policy level. Treat both situations uniformely - with
QubesPropertyAccessError. This allows using convenient `getattr()` to
define placeholder value (if appropriate), or try/except with a single
exception instead of two.
QubesOS/qubes-issues#5105
5cf08b5b03