Promise rejection

[..]
getUserById: (userid) => {
 return new Promise((resolve, reject) => {
  db.getConnection((err, connection) => {
   if (err) {
    return reject(err);
   }

   let sql = 'SELECT * FROM users WHERE userid = ?';
   let param = [userid];
   sql = mysql.format(sql, param);

   connection.query(sql, (err, rows) => {
    if (err) {
     return reject(err);
    }

    resolve(rows);
    connection.release();
   });
  });
 });
}
[..]

// and calling it in route file
[..]
const User = require('../models/user_model').CustomQueries;

router.get('/users/:userid', (req, res, next) => {
 User
  .getUserById(req.params.userid)
  .then((rows) => {
   if (rows.length === 0) {
    res.json({ message: 'No user found.' });
   }
   res.status(200).json(rows);
  })
  .catch((err) => {
   res.json(err);
  });
});