title: Rethrowing error in promise catch
body: <p>I found the following code in a tutorial:</p>
  
  <pre><code>promise.then(function(result){
      //some code
  }).catch(function(error) {
      throw(error);
  });
  </code></pre>
  
  <p>I'm a bit confused: does the catch call accomplish anything? It seems to me that it doesn't have any effect, since it simply throws the same error that was caught. I base this on how a regular try/catch works.</p>