Don't assume existence of event_id in __str__
Don't assume existence of event_id in __str__

matrix-org/synapse,matrix-org/synapse,matrix-org/synapse,matrix-org/synapse,TribeMedia/synapse,TribeMedia/synapse,TribeMedia/synapse,matrix-org/synapse,TribeMedia/synapse,TribeMedia/synapse,matrix-org/synapse