Xvfb unexpectedly quits in Selenium + Node.js app

I use Selenium to check a website for products, and as you can see from the 'top' command, Xvfb and Chromedriver are working fine.

However, Xvfb quits at random. Sometimes at number 40, sometimes at 200, sometimes at 100. Here's a screenshot when it unexpectedly quit at 57. It doesn't appear on the 'top' table anymore, and the app hangs indefinitely:

I use this command to start Xvfb:

Xvfb :1 -screen 0 1024x768x24 -ac +extension GLX +render -noreset

What can I do to keep it running indefinitely? I have deployed the app in a Digital Ocean droplet.

via Athanasios Canko