title: pm2 does not restart worker when express error occur
body: <p>I'm using pm2 to manage process in my nodejs express application (running in cluster mode).</p>
  
  <p>We had 2 kind of error handler</p>
  
  <ul>
  <li><p>FIRST: 'uncaughtException' will be handled with</p>
  
  <pre><code>process.on('uncaughtException', function(err){});
  </code></pre></li>
  </ul>
  
  <p>Actually, I do not declare an handler like this cause of letting pm2 detect died worker in this case so restart the died worker automatically.</p>
  
  <ul>
  <li><p>SECOND: express error handler, I mean the error will be forwarded to express error handler, not uncaughtException handler, the error handler like below</p>
  
  <pre><code>app.use(function(err, req, res, next) {})
  </code></pre></li>
  </ul>
  
  <p>I also do not declare this error handler for same purpose as uncaughtException.
  But pm2 does not restart node in this case.</p>
  
  <p>Any idea about this problem?
  Many thanks</p>