title: How to catch this exception in promise?
body: <p>Consider the following code: particularly when "none" is selected. Using sweetalerts2</p>
  
  <pre><code>Swal.fire({ //
      html: '
      blah blah ',
  
      input: 'select',
      inputOptions: {
        'none': 'Please select an option:',
        'option1': 'First Option',
        'option2': 'Second Option'
      },
      inputValidator: function(value) {
        return new Promise(function(resolve, reject) {
          if (value != 'none') {
            resolve();
          } else {
            reject('You need to select an option');
          }
        });
      }
    }).then(function(theoption) {
        // etc etc...
  </code></pre>
  
  <p>On selecting "none", there is a javascript error. On firefox console, for example, I get
  "uncaught exception: You need to select an option"
  I realise that I am probably la hopeless Newbee</p>