In a production ready web application, it is common that you need to trace errors as they happen. Things can go wrong quite frequently for many reasons. There are tools out there such as https://rollbar.com/ that can make monitoring a joy. Once you integrate it to your site, then you can log exceptions as they appear and get notified in real time. This is very helpful for developers debugging errors. You can view metadata about the exception such as the OS, device, time, commit that introduced the error etc. of the event. Then once you trace the exception, you can easily mark it as done. Monitoring is important in order to keep things in order and retain customer satisfaction. Give it a go they have a free plan. Note, that there are other tools out there such as https://www.papertrail.com/, so make up your mind - compare them and decide which one to use - if any.