TypeError: Super expression must be null or a function, not undefined with Babeljs
Your export doesn't match your import:
export class Point
// and
import Point from './pointES5'
You're exporting a named symbol but importing the default, so you'll be getting the wrong object as Point
in your second file.
You can either use:
export default class Point
in the first class file or
import {Point} from './pointES5';
in the second file to fetch the right reference. If you're going for the single-class-per-file layout, I'd suggest the former. You'll typically only have a single class being exported, so it makes sense to have that as the default.
What you have now is the equivalent of:
// in Point
module.exports = {
Point: Point
};
// in ColorPoint
var Point = require('./pointES5'); // will point to *the whole object*
class SubPoint extends Point