title: mongodb crashed node with exception within try catch
body: <pre><code>try
      p = req.params.name
      Item.update('name': p, req.body , {upsert: true}, (err) -&gt;
        if err?
          throw err
        res.send("ok")
        )
    catch e
      handle_error(e, "Error salvando hoja de vida.", res)
  </code></pre>
  
  <p>This produces an error in my code right now - that's alright, but why does my nodejs program crash even if I have a try catch here?</p>
  
  <p>The error is:</p>
  
  <pre><code>MongoError: Mod on _id not allowed
  </code></pre>
  
  <p>(so it must be in the update call)
  I am specifically looking for a way to catch an error, I already know how to get rid of it.</p>