this doesn't seem to happen that often with this mod in comparison to the other 5 that are affected but it still happens. log (this mostly shows when I generated the world): https://gist.github.com/Nathan22211/3746b2cfbf17ca2d85fc9081dfa26c78

I'm seeing this as well on r1.6-179. Note this is a duplicate of #412 and #986. Seems that it's not really considered a bug.