title: Google Forms Script ItemResponse getScore() returns null
body: <p>Not sure if it is a bug or not, but the <code>getScore()</code> method (<a href="https://developers.google.com/apps-script/reference/forms/item-response#getscore" rel="noreferrer">https://developers.google.com/apps-script/reference/forms/item-response#getscore</a>) always returns <code>null</code> for me, while it is said it should return a <code>double</code>.</p>
  
  <p>The form <strong>is</strong> a Quiz, <strong>does</strong> accept answers, the score is set to <code>2</code> to all questions, the score <strong>is</strong> being registered in the responses in the Google Form.</p>
  
  <pre class="lang-js prettyprint-override"><code>// Code.gs
  
  function onOpen (e) {
    setOnSubmitTrigger();
  }
  
  function setOnSubmitTrigger () {
    var form = FormApp.getActiveForm();
  
    ScriptApp.newTrigger(respondToFormSubmit)
      .forForm(form)
      .onFormSubmit()
      .create();
  }
  
  function respondToFormSubmit (e) {
    var form = FormApp.getActiveForm();
    var allResponses = form.getResponses();
    var response = allResponses[allResponses.length - 1];
    var itemResponses = response.getItemResponses();
  
    console.log(form.isQuiz()); // yields true
  
    for (var i in itemResponses) {
      var itemResponse = itemResponses[i];
  
      Logger.log(itemResponse.getScore()); // (!) always yields null
    }
  }
  </code></pre>
  
  <p>The topic is mentioned in the following questions, but they are neither focused specifically on the issue, nor provide a solution: </p>
  
  <ul>
  <li><a href="https://stackoverflow.com/questions/44751071/how-to-check-if-a-response-is-correct">How to check if a response is correct?</a></li>
  <li><a href="https://stackoverflow.com/questions/40090468/google-forms-get-score-of-respondents-answer">Google forms get score of respondent&#39;s answer</a></li>
  </ul>