Seems that build 204 has a new error in it.
crash-2017-03-07_20.21.25-client.txt
This is occurring when players open their inventory with the E key.

Also just this report as well
crash-2017-03-07_20.54.08-client.txt
That player was in creative mode when it happened if that matters.

NEI's recipe stuff has been nuked as of recently.