Service Worker breaks the app in Firefox

Created by: ketysek

Is this a bug report?

Yes

Did you try recovering your dependencies?

Yes, I've tried it on fresh installed app

Which terms did you search for in User Guide?

service worker, progressive web app

Environment

macOS Mojave (10.14.3), Firefox 66.0 (65.0 worked same), current 2.1.8 react-scripts

Steps to Reproduce

1. create an app (npx create-react-app my-app)
2. update index.js - instead of serviceWorker.unregister() call serviceWorker.register()
3. yarn run build
4. run server with production app code: serve -s -l 3000 build
5. open localhost:3000 in Firefox
6. verify that service worker is activated
7. stop serve server
8. change something (for example text) in App.js
9. yarn run build again
10. run server again
11. refresh the firefox tab with opened app

Expected Behavior

New service worker should be installed and in waiting state

Actual Behavior

It throws error in console and service worker isn't updated:

Failed to register/update a ServiceWorker for scope ‘http://localhost:3000/’: Bad Content-Type of ‘text/html’ received for script ‘http://localhost:3000/precache-manifest.5df49f687d80bec80e0acf86555252db.js’. Must be a JavaScript MIME type.

When I unregister service worker from Firefox and refresh the tab, it's again working for first time - then you refresh the tab (immediately) for the second time and it again throws the same error in console and also crashes (doesn't display the app) with another error in console:

SyntaxError: expected expression, got '<'[Learn More] main.5f3bc8a8.chunk.js:1