Alarm Filter deletion does not run to completion

When issuing a delete of an alarm filter, the AlarmFilterAgent fails while trying to retrieve details on the active filter.

DEBUG MainThread alarm_filter_agent.remove_filter

{event: stopping, instance_id: compose_voltha_1}

DEBUG MainThread alarm_filter_agent._review_filter {alarm_filter: id: "4dfa48062bc7"
rules

{ key: device_id value: "00013912c33acbca" }

, event: reviewing-filter, instance_id: compose_voltha_1}
DEBUG MainThread event_bus_publisher.forward

{event: forward-event-bus-publisher, instance_id: compose_voltha_1}

Unhandled error in Deferred: