Crash when FlxMouseEventManager is used to close a substate with animated sprite

• Haxe version: 3.4.7
• Flixel version: 4.5.1
• OpenFL version: 8.7.0
• Lime version: 7.2.0
• Affected targets: All

Code snippet reproducing the issue:

package;

import flixel.FlxSprite;
import flixel.FlxSubState;
import flixel.graphics.frames.FlxAtlasFrames;
import flixel.input.mouse.FlxMouseEventManager;
import flixel.util.FlxColor;

/**
 * ...
 * @author Tembac
 */
class Substate extends FlxSubState 
{

	public function new(BGColor:FlxColor=FlxColor.TRANSPARENT) 
	{
		super(BGColor);
		
		var textureFrames:FlxAtlasFrames = FlxAtlasFrames.fromTexturePackerJson("assets/images/popUp.png","assets/images/popUp.json");
		
		var closeSpr:FlxSprite = new FlxSprite(128, 128);
		closeSpr.frames = textureFrames;
		closeSpr.animation.addByNames("normal", ["btnCloseNormal"]);
		closeSpr.animation.addByNames("pressed", ["btnOkNormal"]);
		closeSpr.animation.play("normal");
		closeSpr.resetSizeFromFrame();
		add(closeSpr);

		FlxMouseEventManager.add(closeSpr,
		function onMouseDown(s:FlxSprite)
		{
			s.animation.play("pressed");
		},
		function onMouseUp(s:FlxSprite)
		{
			s.animation.play("normal");
			close();
		},
		null,
		function onMouseOut(s:FlxSprite)
		{
			s.animation.play("normal");
		});
		
	}
	
}

Observed behavior:

There is a null reference crash because the mouse out function doesn´t find the sprite to animate.

Expected behavior:

There is no crash.

Example project:

mouseTest.zip

Start by reproducing the crash with the provided mouseTest.zip project and trace the FlxMouseEventManager callbacks used by the FlxSubState close sprite. Done means closing the substate with the animated sprite no longer causes a null-reference crash in the mouse-out callback.