title: Error: Attempt to run compile-and-go script on a cleared scope
body: <p>Since upgrading to Firefox 4.0, I've noticed that I'm occasionally getting an error in the console stating:</p>
  
  <blockquote>
    <p>attempt to run compile-and-go script on a cleared scope</p>
  </blockquote>
  
  <p>The only information I can find about this on the net currently is on the <a href="http://groups.google.com/group/mozilla.dev.platform/browse_thread/thread/10ff69b04b88e06f" rel="noreferrer">mozilla groups forum</a>, where it is suggested that it's something to do with session restoring. In my case, though I haven't been able to reliably reproduce the error, it happens at any time, not just after a restore.</p>
  
  <p>What's the deal? How do I stop the error?</p>