message: logs headers on ratelimit hit
diff: @@ -10,6 +10,7 @@ export class XeroError extends Error {
  const queryobj = querystring.parse(data);
  if (queryobj.oauth_problem && queryobj.oauth_problem_advice) {
  if (statusCode == 503 && headers && headers['x-rate-limit-problem']) {
  + console.log(headers);
  message += ' ' + headers['x-rate-limit-problem'];
  }
  message += ` ${queryobj.oauth_problem} (${queryobj.oauth_problem_advice})`;
  