title: FormApp setPoints does not allow "0" as a value
body: <p>I am writing an App Script using FormApp to reset the values of quiz items to 0. However when I call setPoints(0) it is throwing "Invalid data updating form."</p>
  
  <p>I am trying to set the points of individual items of a form to 0 i.e. basically clear the points of an item. However, when I try to call item.setPoints(0) it is throwing the error of "Invalid data updating form."</p>
  
  <p>Here's my small function that I've written, with dummy form URLs and IDs:</p>
  
  <pre><code>function removePoints() {
    var form = FormApp.openByUrl("https://docs.google.com/forms/d/1CXia_B4h7M2Dk1r8mhTLNyoTrz07dwdty5aiTh5v8QA/edit");
    var items = form.getItems();
    var item = form.getItemById(336898556);
    item.asMultipleChoiceItem().setPoints(0);
  } 
  </code></pre>
  
  <p>Expected results would be to have set 0 points on given item id. 
  But instead, I am getting following error:</p>
  
  <pre><code>Invalid data updating form
  </code></pre>
  
  <p>Is there anything wrong that I am doing? Or is there any other way to reset a item's scores? </p>
  
  <p>Thanks for help in advance. :) </p>