My shepard is roaming around with his two sheep suddenly my footman then starts attacking the sheep for 5 seconds, then teleports randomly everywhere attacking the air and getting damaged then in an attempt to fix problem i save and load the world: my footman is dead with a gravestone the request to join my settlers comes then is whisked away meanwhile the bug reporter window every 0.5 second reports invalid reference in nature my citizen menu has no citizens in it???
TZAH 
@tzah, sounds like a known bug in the unstable release. Opt out of the betas in Steam and reinstall the Alpha 6 release to get a more stable game. I think they said in one of their dev streams that they expect the stable Alpha 7 release to be out in a couple of weeks (early January.)
(to be merged with existing report)