This post is intended to help anyone who runs into the same problem: after updating from 1.8.1 to 1.8.3, I got this error when starting one of my applications:
Cannot find module … node_modules@babel\runtime\hepers\objectSpread2
I tried multiple “meteor updates” but that didn’t fix it. I also tried “meteor update --all-packages”, which did nothing even though there are multiple packages listed with updates available.
What eventually fixed this was “npm update”, which installed “@firstname.lastname@example.org” – and the problem went away!