message: Avoid undefined behavior by checking for null Operation in TF_Input/TF_Output
diff: @@ -54,7 +54,7 @@ Status ProcessInputs(
  TF_EXCLUSIVE_LOCKS_REQUIRED(fn_body->mu) {
  input_tensors->reserve(ninputs);
  for (int i = 0; i < ninputs; ++i) {
  - Node* node = &inputs[i].oper->node;
  + Node* node = inputs[i].oper ? &inputs[i].oper->node : nullptr;
  int idx = inputs[i].index;
  TF_RETURN_WITH_CONTEXT_IF_ERROR(
  @@ -90,7 +90,7 @@ Status ProcessOutputs(const TF_Graph* fn_body, const char* fn_name,
  TF_EXCLUSIVE_LOCKS_REQUIRED(fn_body->mu) {
  output_tensors->reserve(noutputs);
  for (int i = 0; i < noutputs; ++i) {
  - Node* node = &outputs[i].oper->node;
  + Node* node = outputs[i].oper ? &outputs[i].oper->node : nullptr;
  int idx = outputs[i].index;
  TF_RETURN_WITH_CONTEXT_IF_ERROR(
  fn_body->graph.IsValidOutputTensor(node, idx),
  