added logic to deal with an insutrment with no placeables associated with it
added logic to deal with an insutrment with no placeables associated with it

OpenTrons/opentrons-api,Opentrons/labware,OpenTrons/opentrons_sdk,OpenTrons/opentrons-api,OpenTrons/opentrons-api,OpenTrons/opentrons-api,OpenTrons/opentrons-api