title: Spring Integration, catching exception on error channel prevents return
body: <p>I have a set of simple REST services which are all configured with an <code>error-channel</code> to allow a <code>service-activator</code> specified bean to catch exceptions. </p>
  
  <p>When an exception does occur, the method in the bean is called, as expected, and I log the exception. However, the caller (i.e. HTTP client) never gets a response. </p>
  
  <p>What do I need to do to return some sort of error (or indeed anything) back to the client?</p>
  
  <p>I'm assuming I'm missing something obvious!</p>