Fix bug where we were leaking None into state event lists
Fix bug where we were leaking None into state event lists

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