I get the same error (console-spam) as soon as i enter the trader.
Log says:
NullReferenceException: Object reference not set to an instance of an object
at EntityNPC.OnUpdateLive () [0x00000] in <filename unknown>:0
at EntityAlive.OnUpdateEntity () [0x00000] in <filename unknown>:0
at World.TickEntities (Single _partialTicks) [0x00000] in <filename unknown>:0
at GameManager.DA () [0x00000] in <filename unknown>:0
at GameManager.Update () [0x00000] in <filename unknown>:0
P.S. Thank you Spieder for the hard work on this mod - i don´t play vannila 7d2d anymore - its just a basics tutorial for your masterpiece