Update src/url_aggregator.cpp

src/url_aggregator.cpp

@@ -286,6 +286,7 @@ bool url_aggregator::set_port(const std::string_view input) {
     return true;
   }
 
+  // Input should not start with a non-digit character.
   if (!ada::unicode::is_ascii_digit(trimmed.front())) {
     return false;
   }