message: instancedPrimitiveJsonFiles are optional
diff: @@ -324,6 +324,8 @@ void load_moana(std::string const& filename, model& mod)
  // instancedPrimitiveJsonFiles
  + try
  + {
  for (auto& v : pt.get_child("instancedPrimitiveJsonFiles"))
  {
  std::string type = v.second.get<std::string>("type");
  @@ -335,6 +337,12 @@ void load_moana(std::string const& filename, model& mod)
  load_instanced_primitive_json_file(island_base_path, inst_json_file, base_transform, materials);
  }
  }
  + }
  + catch (...)
  + {
  + // Nothing to handle, just no instancedPrimitiveJsonFiles present
  + // (property_tree.get_child() throws)
  + }
  // instandedCopies (TODO: support copies with other geometry!)
  