title: No errors with express-validator isEmpty
body: <p>I am using express-validator 5.2.0 in a expressjs app. I implemented the validaiton on a form data. But it does not capture the errors and gives empty errors object. When validation runs it shows the "no error" when I submit the empty form. It should follow the error path and should display the error.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>var express = require('express');
  var router = express.Router();
  const { check, validationResult } = require('express-validator/check');
  
  router.post('/register', [
    check('firstName', 'First Name is required').isEmpty(),
    check('lastName', 'Last Name is required').isEmpty(),
    check('username', 'User Name is required').isEmpty(),
    check('password', 'Password is required').isEmpty()
  ], (req, res, next)=&gt;{
    let errors = validationResult(req);
    if (!errors.isEmpty()) {
      console.log(errors.mapped());
      console.log("errors")
      return res.render('auth/register', { errors: errors.mapped() })
    }else{
      console.log('no errors')
      return res.render('auth/login');
    }</code></pre>
  </div>
  </div>
  </p>