message: Return error instead of checking in GraphToFunctionDef.
diff: @@ -153,7 +153,7 @@ Status GraphToFunctionDef(const Graph& graph, const string& name,
  const string normalized = node_names.Normalize(node->name());
  argdef->set_name(normalized);
  Edge const* edge;
  - TF_CHECK_OK(node->input_edge(0, &edge));
  + TF_RETURN_IF_ERROR(node->input_edge(0, &edge));
  return_values[normalized] =
  strings::StrCat(edge->src()->name(), ":", edge->src_output());
  continue;
  