Description
This is just a placeholder ticket -- the bug is not in the nodemcu code, but (I think) in the espressif SDK. I have opened a bug with them, although the bug is not very reproducible.
There are other people (try https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=lmacprocessacktimeout), with non-nodemcu codebases, and with older versions of the SDK that have seen the same crash -- lmacProcessAckTimeout+39 (decimal).
It causes my app to crash roughly once every 4 to 8 hours. It appears to be position dependent -- if I move the board from one location to another, the failure rate goes up or down. The AP is positioned a long way away, so the signal is weak to begin with.
If you have unexplained crashes, then use the improved node.bootreason() from issue #900 to get the failing PC. Then you can look in your mapfile to find the failing function.
Just to repeat, this is probably not a bug in the nodemcu code, but it is a bug that affects the users of nodemcu.