Nested ES6 generator crashes or errors in Safari when console opened or closed?

Question

Writing a generator that yield*s inside another generator every rAF (in order to do some event sequences on various conditions and timings), normally it works fine. But when I open or close the console in Safari, the generator stops working (or worse).

It either crashes the browser or throws the error: "TypeError: yield* subGenerator is not a function. (In 'yield* subGenerator()', 'yield* subGenerator' is undefined)"

I've looked around a bunch but I can't find related info. I've tried assigning the subgenerator to a var, and logging the related objects to turn up extra info, but didn't find any hints.

    mainGenerator = function*() {
      while (true) {
        yield* subGenerator()
      }
    }
    
    subGenerator = function*() {
      while (true) {
        yield
      }
    }
    
    update = function() {
      generatey.next()
      window.requestAnimationFrame(update.bind(this));
    
    }
    var generatey = mainGenerator();
    window.requestAnimationFrame(update.bind(this));

JSFiddle HERE: https://jsfiddle.net/hvofwk0z/

Run, THEN open (or close) console to see the generator will stop, sometimes with an error, sometimes crashing the tab.

Not being able to open/close the console without breaking the page is making debugging difficult.

Is there something I'm missing? Am I making a mistake here somewhere? Or is this a universal es6 bug?