Draft: Workbox
Summary
Start converting the ServiceWorker over to Workbox: https://developer.chrome.com/docs/workbox/modules/workbox-webpack-plugin/
offline-plugin is "maintained" by a pharmacy in France, while Workbox is maintained by Google. So we'll likely have better luck with it.
Also, Workbox makes less assumptions about what you want. It gives you tools to make it easier to write a SW file, rather than trying to generate it for you.