message: Log an error in GrapplerItemFromMetaGraphDefFile if we fail to load the model file.
diff: @@ -645,6 +645,7 @@ std::unique_ptr<GrapplerItem> GrapplerItemFromMetaGraphDefFile(
  const string& id, const string& meta_graph_file, const ItemConfig& cfg) {
  MetaGraphDef meta_graph;
  if (!ReadMetaGraphDefFromFile(meta_graph_file, &meta_graph).ok()) {
  + LOG(ERROR) << "Failed to read " << meta_graph_file;
  return nullptr;
  }
  return GrapplerItemFromMetaGraphDef(id, meta_graph, cfg);
  