Handle error when timer called on stale object
Handle error when timer called on stale object

* `self` may refer to an objref proxy, in which case checking the
  `stale` property already fails when attempted outside a request
  context

yelworc/eleven-server,ElevenGiants/eleven-server,KaiyonAlatar/eleven-server,KaiyonAlatar/eleven-server,KaiyonAlatar/eleven-server,yelworc/eleven-server,ElevenGiants/eleven-server,Whizy/eleven-server,ElevenGiants/eleven-server,Whizy/eleven-server,Whizy/eleven-server