Poloniex cancelfix crashes

[askmike]

I have been battling a very strange and hard to come by error on poloniex:

• Gekko Broker cancels an order
• Poloniex responds with a timeout error, meaning that the cancel might have been processed, or it might not have been.
• Gekko fetches recent orders to see if the order is still open.
• if still open: it wasn't processed, trigger a retry.
• if it's NOT: it was cancelled, great! Gekko Broker now expects to know whether there were partial fills up until the cancel got processed. use getOrder to figure this out.

This latest NOT step only happens rarely (roughly once every 1,036,800 cancel calls on the market I am trading with my current server) so debugging is hard. But it just happened with:

2018-07-29T05:19:23.984Z '[CANCELFIX] process cancel response'
[CANCELFIX] rechecking fill
timers.js:379
    throw new ERR_INVALID_CALLBACK();
    ^

TypeError [ERR_INVALID_CALLBACK]: Callback must be a function
    at setTimeout (timers.js:379:11)
    at getOpenOrders (/root/gb/wrappers/poloniex.js:134:15)
    at checkFn (/root/gb/exchangeUtils.js:23:16)
    at /root/gb/node_modules/lodash/lodash.js:10050:25
    at /root/gb/wrappers/poloniex.js:173:12
    at Request._callback (/root/gb/node_modules/poloniex.js/lib/poloniex.js:80:7)
    at Request.self.callback (/root/gb/node_modules/poloniex.js/node_modules/request/request.js:122:22)
    at Request.emit (events.js:182:13)
    at Request.<anonymous> (/root/gb/node_modules/poloniex.js/node_modules/request/request.js:888:14)
    at Request.emit (events.js:187:15)