When unit is chasing someone and target dies, unit receives movement update with likelyFailure, but that case is not handled, so unit is stuck in chasing state forever.
Handling that case similar as in approaching. However as unit can run after fleeing target, it has to run to the its last known position instead walking because that would mean leaking information of target dead and that was refused to do earlier.
In order to approach target last seen position new substate is used to keep potential animation variant in tact and to keep current speed without additional checks, also this helps keep combat "Attacked" logic in case unit is attacked while finishing chasing.