The board server hangs after some time. This error:
file:///root/whiteboard/websocket_server/SocketManager.js:160
user: data.user,
^

TypeError: Cannot read properties of undefined (reading 'user')
at file:///root/whiteboard/websocket_server/SocketManager.js:160:16
at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
at async Promise.all (index 0)
at async SocketManager.joinRoomHandler (file:///root/whiteboard/websocket_server/SocketManager.js:170:29)

What can be checked or corrected? Thank you.