SYWEB-102: Fix desktop notification msg when a user with no display name joins a room.
SYWEB-102: Fix desktop notification msg when a user with no display name joins a room.

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