Crash with TypeError: Cannot read property '0' of undefined

[bpfh]

Hello,

My scrumblr installation crashes frequently with the following stack trace:

client: 21098831311167855338 is broadcasting to: 
setBoardSize -- { width: 996, height: 747 }

/root/tmp/scrumblr/lib/rooms.js:131
                return client_rooms[0];
                     ^
TypeError: Cannot read property '0' of undefined
    at Object.get_room (/root/tmp/scrumblr/lib/rooms.js:131:22)
    at getRoom (/root/tmp/scrumblr/server.js:469:15)
    at Socket.<anonymous> (/root/tmp/scrumblr/server.js:312:5)
    at Socket.$emit (events.js:67:17)
    at SocketNamespace.handlePacket (/root/tmp/scrumblr/node_modules/socket.io/lib/namespace.js:353:20)
    at Manager.onClientMessage (/root/tmp/scrumblr/node_modules/socket.io/lib/manager.js:459:38)
    at JSONPPolling.onMessage (/root/tmp/scrumblr/node_modules/socket.io/lib/transport.js:387:20)
    at JSONPPolling.<anonymous> (/root/tmp/scrumblr/node_modules/socket.io/lib/transports/http.js:89:10)
    at JSONPPolling.onData (/root/tmp/scrumblr/node_modules/socket.io/lib/transports/jsonp-polling.js:72:32)
    at IncomingMessage.<anonymous> (/root/tmp/scrumblr/node_modules/socket.io/lib/transports/http.js:60:12)

The problem started appearing recently with no changes to the scrumblr installation, so I suspect corrupt data somewhere. Any tips?

Thanks!