TypeError: Cannot read property 'toLowerCase' of undefined

[thom4parisot]

I just deployed a new bot in a private channel, started a retro and never received any DM from the bot:

I inspected the logs and found this:

2017-03-03T13:48:51.444971+00:00 app[worker.1]: TypeError: Cannot read property 'toLowerCase' of undefined
2017-03-03T13:48:51.444972+00:00 app[worker.1]:     at Object.handleMessage (/app/lib/index.js:160:12)
2017-03-03T13:48:51.444973+00:00 app[worker.1]:     at Array.forEach (native)
2017-03-03T13:48:51.444973+00:00 app[worker.1]:     at /app/node_modules/slack/methods/rtm.client.js:60:22
2017-03-03T13:48:51.444971+00:00 app[worker.1]:     at command (/app/lib/index.js:217:12)
2017-03-03T13:48:51.444974+00:00 app[worker.1]:     at WebSocket.message (/app/node_modules/slack/methods/rtm.client.js:59:20)
2017-03-03T13:48:51.444975+00:00 app[worker.1]:     at emitTwo (events.js:106:13)
2017-03-03T13:48:51.444975+00:00 app[worker.1]:     at WebSocket.emit (events.js:191:7)
2017-03-03T13:48:51.444977+00:00 app[worker.1]:     at /app/node_modules/ws/lib/Receiver.js:536:18
2017-03-03T13:48:51.444976+00:00 app[worker.1]:     at Receiver.ontext (/app/node_modules/ws/lib/WebSocket.js:841:10)
2017-03-03T13:48:51.444977+00:00 app[worker.1]:     at Receiver.applyExtensions (/app/node_modules/ws/lib/Receiver.js:371:5)

[thom4parisot]

I restarted the heroku app and the problem no longer exists.

It seems none of the 3 members of the channel received a retrobot DM invite.
When I talk to the bot by DM, it responds to me with the following message:

Another channel is currently running a retrospective and your invite got lost in the mail, sincerest appologies, retrobot xx