public void SetNthMask(int index, object obj) { MasterReference_FieldIndex enu = (MasterReference_FieldIndex)index; switch (enu) { case MasterReference_FieldIndex.Master: this.Master = (Exception?)obj; break; case MasterReference_FieldIndex.FileSize: this.FileSize = (Exception?)obj; break; default: throw new ArgumentException($"Index is out of range: {index}"); } }