trying to avoid/cleanup having to check
val := reflect.ValueOf(s)
k := val.Kind()
if k == reflect.Invalid { // any way to avoid this and still get `var err error` to return null?
return nullString
}
and more directly find nil interfaces like var err error
https://github.com/fortio/log/blob/build_tags/no_json_logging.go#L91-L92
@dry dragon