Ensure we never return a None event from _get_state_for_groups
Ensure we never return a None event from _get_state_for_groups

iot-factory/synapse,matrix-org/synapse,rzr/synapse,matrix-org/synapse,TribeMedia/synapse,TribeMedia/synapse,matrix-org/synapse,TribeMedia/synapse,rzr/synapse,rzr/synapse,iot-factory/synapse,matrix-org/synapse,TribeMedia/synapse,iot-factory/synapse,rzr/synapse,iot-factory/synapse,iot-factory/synapse,TribeMedia/synapse,matrix-org/synapse,matrix-org/synapse,rzr/synapse