Going from one scene to next and gettingType1009 Null object reference errors

Question

Okay so in my main menu for my game, I have a glow effect so that when you hover over the invisible button 'startdesu', the script will make the whole menu glow, fading in and out. This code (from the event listener onwards) has been repeated for each button on the menu, with appropriate changes to the button instance name and the function names. The only problem is, when I click 'startdesu' and it takes me to the next scene, I start getting repetitive errors, "TypeError: Error #1009: Cannot access a property or method of a null object reference. at bjvb_fla::MainTimeline/increaseGlow()". I've tried removing the glow event listeners when the buttons are clicked and everything but no luck. Please help! ;0;

Here is the essential code for brevity's sake, but I can post the whole thing if it helps. (also, i get the same Null error for something else when i go from the game back to the start menu.

import flash.filters.*;
import flash.events.Event;

stop();
wow.alpha=0.5;

var menuGlow:GlowFilter = new GlowFilter();

menuGlow.color = 0xffffff;

menuGlow.blurX = 20;

menuGlow.blurY = 20;

menuGlow.alpha = 0;

menu.filters = [menuGlow];

var glow:Boolean = false;


startdesu.addEventListener(MouseEvent.MOUSE_OVER, addGlow);
startdesu.addEventListener(MouseEvent.MOUSE_OUT, removeGlow);
startdesu.addEventListener(Event.ENTER_FRAME, increaseGlow);

function addGlow(e:MouseEvent):void
{
glow = true;
}

function removeGlow(e:MouseEvent):void
{
glow = false;    
}

function increaseGlow(e:Event):void
{
if(glow == true)
{

    menuGlow.alpha = menuGlow.alpha + 0.02;
}
else if(glow == false)
{
    menuGlow.alpha = menuGlow.alpha - 0.02;
}
menu.filters = [menuGlow];
}

Answer 1

This is the line that is likely causing the error:

menu.filters = [menuGlow];

There is probably no object with the instance name 'menu' in your second scene. You could fix the error by just adding a check if the object exists, like so:

function increaseGlow(e:Event):void
{
    //if there's no menu object, return
    if(!menu) return;

    if(glow == true) {
        menuGlow.alpha = menuGlow.alpha + 0.02;
    } else {
        menuGlow.alpha = menuGlow.alpha - 0.02;
    }
    menu.filters = [menuGlow];
}

But the correct solution would be to remove the event listeners. Not sure why it didn't work for you, but you should be able to just add this in the click event handler before you switch your scene.

startdesu.removeEventListener(Event.ENTER_FRAME, increaseGlow);

What errors do you get when you try to remove the event listener?