Yep, like dkrvt mentioned I'm using sw-precache to generate the server worker file. The file in my root folder that you're seeing is sort of a placeholder which gets copied to the actual bundle folder that gets deployed (you don't see it in the GitHub repo, you'll need to build the app locally [ng build --prod] to generate it]. sw-precache then lets me run a simple command which sets up the service worker on the fly based on some simple configurations.

Here's an excellent article btw that helped me understand how to set up sw-precache with an Angular CLI app (https://coryrylan.com/blog/fast-offline-angular-apps-with-se...)