Service Worker not caching the index file

[Mcgurk-Adam]

Describe the bug - Because we were trying to create the freshest content for the index file, we aren't caching it or returning it from the cache at all, so when someone navigates to it with a poor (or no) internet connection, the page just crashes and says 'something went wrong'. We need to be caching all necessary files and returning them in this way: network, falling back to cache: https://developers.google.com/web/fundamentals/instant-and-offline/offline-cookbook/#network-falling-back-to-cache

To Reproduce Steps to reproduce the behavior:

Make sure you've navigated to signatures.shinesolar.com before, then turn your wifi off. Now navigate there again. You should see the issues

Version:

OS w/ version: macOS Mojave version 10.14.1
Browser w/ version: Chrome 71

[Mcgurk-Adam]

Made an update in commit #54 that fetches from network and falls back to cache. The problem is, I'm getting errors thrown in the console when I try to access the site offline, saying "something went wrong"

Check in a different browser