Root level exception in OnGUI(): System.ArgumentNullException: Argument cannot be null. Parameter name: type at System.Activator.CheckType (System.Type type) [0x00000] in <filename unknown>:0 at System.Activator.CreateInstance (System.Type type, Boolean nonPublic) [0x00000] in <filename unknown>:0 at System.Activator.CreateInstance (System.Type type) [0x00000] in <filename unknown>:0 at Verse.ThingMaker.MakeThing (Verse.ThingDef def, Verse.ThingDef stuff) [0x00000] in <filename unknown>:0 at RimWorld.Designator_Build.DesignateSingleCell (IntVec3 c) [0x00000] in <filename unknown>:0 at Verse.DesignatorManager.ProcessInputEvents () [0x00000] in <filename unknown>:0 at RimWorld.MapInterface.HandleMapClicks () [0x00000] in <filename unknown>:0 at RimWorld.UIRoot_Play.UIRootOnGUI () [0x00000] in <filename unknown>:0 at Verse.Root.OnGUI () [0x00000] in <filename unknown>:0 Verse.Log:Error(String, Boolean) Verse.Root:OnGUI()