message: Don't try to write object if LcfSize is 0
diff: @@ -122,9 +122,12 @@ void Struct<S>::WriteLcf(const S& obj, LcfWriter& stream) {
  continue;
  }
  stream.WriteInt(field->id);
  - stream.WriteInt(field->LcfSize(obj, stream));
  + auto len = field->LcfSize(obj, stream);
  + stream.WriteInt(len);
  + if (len > 0) {
  field->WriteLcf(obj, stream);
  }
  + }
  // Writing a 0-byte after RPG::Database or RPG::Save breaks the parser in RPG_RT
  conditional_zero_writer<S>(stream);
  }
  