message: Remove superfluous assert()
  Same thing tested with CHECK_GT() right above. Also, prefer
  CHECK() to assert()
diff: @@ -225,7 +225,6 @@ static void ColumnsTreeFormatter(
  auto extra_width = node.Value().width - children_width;
  for (auto& child : node.Children()) {
  CHECK_GT(children_width, 0);
  - assert(children_width > 0);
  const auto added_child_width =
  extra_width * child.Value().width / children_width;
  extra_width -= added_child_width;
  