Strange error: missing core-js

I’m not sure what’s going on. I have a Meteor 1.4 app that I updated to 1.5. The upgrade went fine with no complaints. When I run the app, I get a blank page and in the console I see ‘missing core-js’.

Since Meteor 1.4 already supports ES6 and I was using those features already, I don’t understand why this happened.

Try running:

meteor npm install --save babel-runtime