Make instanceof throw an error instead of panic()ing
Make instanceof throw an error instead of panic()ing

We don’t really need instanceof so continue to punt on implementing it,
but it shouldn’t crash the system.

google/CodeCity,google/CodeCity,google/CodeCity,NeilFraser/CodeCity,NeilFraser/CodeCity,NeilFraser/CodeCity,google/CodeCity,NeilFraser/CodeCity