Exception in Sim Timeline: Exception resuming Element (RuntimeError: Deleted sim: found in required sims of interaction: running npc_leave_lot_now_must_run_ss3_request:4137 on None  (guaranteed) PipelineProgress.QUEUED None)
Traceback (most recent call last):
  File "T:\InGame\Gameplay\Scripts\Server\scheduling.py"

def _get_head(self):
        self.clear_head_cache()
        self._head_cache = None
        next_unblocked_interaction = None
        for bucket in self._buckets:
            next_unblocked_interaction = bucket.get_next_unblocked_interaction(blocked_sims_callback=self._set_si_state_on_changed_callbacks_for_head)
            while next_unblocked_interaction is not None:
                break
        if self._head_cache is not None and self._head_cache is not UNSET:
            return self._head_cache
        if next_unblocked_interaction is not None:
            required_sims = WeakSet(next_unblocked_interaction.required_sims())

            def clear_and_remove(si, self_ref=weakref.ref(self)):
                for sim in required_sims:
                    while sim.si_state is not None:
                        sim.si_state.on_changed.remove(clear_and_remove)
                self = self_ref()
                if self is not None:
                    self.clear_head_cache()

            for sim in required_sims:
                while sim.si_state is not None:
                    sim.si_state.on_changed.append(clear_and_remove)
            for sim in required_sims:
                while sim.si_state is None:
                    raise RuntimeError('Deleted sim:{} found in required sims of interaction:{} {} {}'.format(sim, next_unblocked_interaction, next_unblocked_interaction._pipeline_progress, next_unblocked_interaction._required_sims))
        self._head_cache = next_unblocked_interaction
        return next_unblocked_interaction