HTML5 target error HandleWindowEvent Critical error

I’m fully up to date, Haxe 3.4.4, Openfl 6.5.0, Lime 5.8.2 , and am seeing a new error in html5 target code across all browsers i test on.

In IE 11, it occurs during loading and prevent the game from running.
In Chrome 62 and Firefox 57 it only occurs when leaving the game (e.g. if a page is refreshed the error will pop up briefly).

IE error , SCRIPT5007: Unable to get property ‘onClose’ of undefined or null reference

      handleWindowEvent: function(event) {
		if(this.parent.__windows[0] != null) {
			var _g = event.type;
			switch(_g) {
			case "beforeunload":
				if(!event.defaultPrevented) {
					this.parent.__windows[0].onClose.dispatch();
					if(this.parent.__windows[0].onClose.canceled) {
		Unable to get property 'onClose' of undefined or null reference
						event.preventDefault();
					}
				}
				break;

it seems that this.parent.__windows[0].onClose.dispatch(); makes this.parent.__windows[0] empty !

i noticed it too but it is happens when i refresh the page so i ignore it cause it is not stopping anything in the app itself.

Have you tested on IE ? it occurs during asset loading for me, preventing the app running !

IE = only happens one time : image
but i am in doubt it has something to do with the app. because it never happened again.

Firefox = whenever you press refresh button
image

Chrome = it just disappear and do nothing but one thing to consider in all cases it happens first before loading anything.

also if you check my last post Preloading Issue with my app

this solves the problem for me may be you should try it.

image

Thanks, should be fixed here: