Circular structure error

[loleg]

Not sure what is happening here, but it seems to lead to disconnects.

ERROR TypeError: Converting circular structure to JSON
    at JSON.stringify (<anonymous>:null:null)
    at Brain.<anonymous> (/srv/soda/sodabotnik/node_modules/hubot-redis-brain/src/redis-brain.coffee:75:42)
    at emitOne (events.js:96:13)
    at Brain.emit (events.js:191:7)
    at Brain.save (/srv/soda/sodabotnik/node_modules/hubot/src/brain.coffee:54:6)
    at Timeout._onTimeout (/srv/soda/sodabotnik/node_modules/hubot/src/brain.coffee:80:8)
    at ontimeout (timers.js:386:14)
    at tryOnTimeout (timers.js:250:5)
    at Timer.listOnTimeout (timers.js:214:5)