message: Fix assertion on iterator position
diff: @@ -73,7 +73,7 @@ config_option::config_option(string_view category, string_view name,
  short_names_separator_ = pos();
  *i++ = ',';
  // <description>
  - copy(description.begin(), description.end(), i);
  + i = copy(description.begin(), description.end(), i);
  CAF_ASSERT(pos() == buf_size_);
  }
  