message: fix triangular matrix generator
diff: @@ -244,7 +244,7 @@ std::unique_ptr<MatrixType> generate_random_triangular_matrix(
  }
  // add diagonal if it hasn't been added yet
  - if (!has_diagonal) {
  + if (!has_diagonal && row < num_cols) {
  auto val = ones_on_diagonal ? one
  : detail::get_rand_value<value_type>(
  value_dist, engine);
  