Manifest.json for progressive web app not working
First issue, your start_url is not valid. You should learn to use how to generate Lighthouse report to help yourself find such issue cause.
Instead of having start URL as this
"start_url": "./index.html",Try this or simply remove "." from the above URL and try, it all depends on your build and hosting, manifest and index.html locations, etc. So you have to try multiple and see what works.
"start_url": "http://tabbs-web-app.herokuapp.com/discover/home",I'm not getting the error that you have mentioned.I'm getting the below one though, which is because your site loads content from non HTTPS requests. If you are targeting to make your site a PWA one, convert all HTTP request over HTTPS and add a service worker.
Site cannot be installed: the page is not served from a secure originHere is the Lighthouse audit report, which says Manifest is not 