Used the "error" argument for log argument

[peterweb2005]

eg:

    log.finest('now: ', now);

when printing

      if (record.error != null) {
        buffer.write(record.error);
      }

so the problem is i dont know whether it is null or empty string, anyway to

  void finest(message, [dynamic error = '', StackTrace stackTrace]) =>
      log(Level.FINEST, message, error, stackTrace);

make the error default empty string