Inheriting from the Error object - where is the message property?

Question

I noticed a strange behavior while defining custom error objects in Javascript:

function MyError(msg) {
    Error.call(this, msg);
    this.name = \"MyError\         


        

Answer 1

What's wrong with doing it this way in ES6?

class MyError extends Error {
    constructor(message) {
        super(message);
        // Maintains proper stack trace (only on V8)
        if (Error.captureStackTrace) {
            Error.captureStackTrace(this, MyError);
        }
        this.appcode= 123; // can add custom props
    }
}