Hmmm… found the solution. Very anticlimactic. In short, I deleted the package-lock.json.
No need to install anything else (node-sass, windows-build-tools, etc…)
I created a new project and in which npm install works just fine. Then I started copying files from the faulty project to the new until it caused the crash. When I transferred package-lock.json, that’s where it crashed. So I deleted it and ran npm install again. Worked fine.
So I went in my old project and renamed package-lock.json to package-lock-old.json (to be able to compare). npm install works just fine now and I’m able to run ionic serve fine also.
I ran a comparison between the two package-lock files and here is the major difference:
Updated version of firebase from 5.5.5 to 5.7.0 with a dependency upgrade from grpc 1.13.1 to 1.16.1
It’s one of those solutions where you spend a good minute blinking at the screen and wishing you could get your day back.