I was looking at this a few weeks ago and it seemed that if any pathway of the code referenced this prior to executing super(), the reference error would occur. I believe that is the extent of the problem.
Do you see any more complexity in the problem beyond that?

I also agree with your first approach.

No, I think that's it. I was wondering whether one could define a function internally using this that you could call before super() - but I think it's not possible. Well... you could call functions that use this before super(), but the this would be referencing something else than the current object.

We also need to watch out for false-positives. The following code is valid:

constructor() {
    var foo = function() {
        return this;
    };
    super();
    foo.call(this);
}

But this is not:

constructor() {
    var foo = () => {
        return this;
    };
    super();
    foo();
}

Which I think simply comes down to that we should not look for this inside normal functions - only inside arrow-functions.