message: [tflite] Fix null pointer dereference introduced in
diff: @@ -261,11 +261,15 @@ absl::optional<uint64_t> VerifyAndCountSparseElements(const Tensor& tensor) {
  }
  const int block_rank = total_dims - original_rank;
  - const int sparsity_block_map_size = sparsity->block_map()->size();
  - if (block_rank > 0 && (sparsity->block_map() == nullptr ||
  - sparsity_block_map_size != block_rank)) {
  + if (block_rank > 0) {
  + if (sparsity->block_map() == nullptr) {
  return absl::nullopt;
  }
  + const int sparse_rank = sparsity->block_map()->size();
  + if (sparse_rank != block_rank) {
  + return absl::nullopt;
  + }
  + }
  // For a n-dimensional tensor (d0, ..., dn-1) with k-dimensional block (dn,
  // ..., dn+k-1), the first n elements in the traversal order should be a
  