title: groovy empty list exception
body: <p>This works perfectly if the <em>priobann</em> list is populated:</p>
  
  <pre><code>banns &lt;&lt; priobann?.pop()
  </code></pre>
  
  <p>However, if it's empty, I get the exception: java.util.NoSuchElementException: Cannot pop() an empty List</p>
  
  <p>Shouldn't the question mark after priobann avoid this exception ?</p>