title: Wirecloud / FI-ware Widget: Exception catched input endpoint
body: <p>I'm working on a widget for the mashup platform at fi-ware.
  Until now it worked very well, but after I made a few tweaks at the code it says when it gets executed that </p>
  
  <pre><code>Exception catched while processing an event that reached the "input" input endpoint
  </code></pre>
  
  <p>But I use the registerCallback method with input as paramter, so I don't know where the problem is.</p>
  
  <p>Is there another reason to get one of these exceptions?</p>