NullReferenceException: Object reference not set to an instance of an object
  at PartLoader.SetFogFactor (UnityEngine.GameObject model, Single fogFactor) [0x00000] in <filename unknown>:0

  at PartLoader.ParsePart (.UrlConfig urlConfig, .ConfigNode node) [0x00000] in <filename unknown>:0

  at PartLoader+.MoveNext () [0x00000] in <filename unknown>:0