Add a route that does something like

  throw new Error('Uh oh')

Error handling done right will include a way to catch the error. With current versions of Node.js that means to use domains.

And then you want to make sure that a crash will not cause other concurrent connections to get abruptly disconnected.

I have a few things in place that I use to get zero-downtime deploys and crash handling.

https://github.com/mathrawka/express-graceful-exit

https://github.com/mathrawka/express-domain-errors

https://github.com/superjoe30/naught