message: Change log level for error iin ShallKeepControlEdgeFrom
diff: @@ -106,7 +106,7 @@ std::pair<TfGpuId, PlatformGpuId> GetFirstValidDeviceId() {
  // Returns false for const nodes (we intend to drop control edges from those).
  bool ShallKeepControlEdgeFrom(const Node* input_node) {
  if (!input_node) {
  - VLOG(2) << "Node pointer is null, this should not happen";
  + LOG(FATAL) << "Node pointer is null, this should not happen";
  return false;
  }
  return input_node->type_string() != "Const";
  