message: Fix nullptr dereference when `out_shape_flat` is empty.
diff: @@ -320,8 +320,10 @@ class SparseReduceSparseOp : public OpKernel {
  &out_shape_t));
  auto out_shape_flat = out_shape_t->flat<int64>();
  auto out_dim_sizes = reduction.reduced_shape.dim_sizes();
  + if (!out_dim_sizes.empty()) {
  std::copy(out_dim_sizes.begin(), out_dim_sizes.end(), &out_shape_flat(0));
  }
  + }
  private:
  // True if the number of dimensions should be maintained.
  