Panic when calling AckErrorEvent.Error() about slack

[mkarlesky]

We started seeing this same issue this morning. Concurrently, Slack has been having major platform outage issues all day.

It appears that the issue is related to the JSON Slack is sending back for an ACK. It's {}. The unmarshalling in handleAck() in websocket_managed_conn.go was not handling empty JSON well and led to a nil panic.

@falzm After checking our vendored version of the library against what's up to date in the repo, we saw that the newer code is smarter about this. We're now experimenting with updating our version of nlopes/slack.

[doertedev]

Any updates on this issue? :(

[mkarlesky]

The latest code in the repo as of the time of my comment had proper protections for the issue we were experiencing. Once we updated our vendored library (it was almost a year old) the problem was solved.

[dvdplm]

@mkarlesky thank you for reporting back. I'm going to close this issue as fixed then.