message: Don't concatenate empty tensors
diff: @@ -435,8 +435,10 @@ class TensorListConcat : public OpKernel {
  for (int i = 0; i < tensor_list->tensors().size(); i++) {
  const Tensor& element_tensor = tensor_list->tensors()[i];
  if (element_tensor.dtype() != DT_INVALID) {
  + if (element_tensor.NumElements() > 0) {
  inputs_flat.emplace_back(new typename TTypes<T, 2>::ConstMatrix(
  element_tensor.shaped<T, 2>({1, element_tensor.NumElements()})));
  + }
  } else {
  AllocatorAttributes attr;
  if (element_dtype_ == DT_VARIANT) {
  