Strange issue with preloader - actionscript-3

Question

I have some problem with my preloader.
Preloader Code:
import flash.net.URLRequest;
import flash.display.Loader;
import flash.events.Event;
import flash.events.ProgressEvent;
var game:MovieClip
var added:Boolean;
var mLoader:Loader = new Loader();
var mRequest:URLRequest = new URLRequest("source.swf");
mLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, onCompleteHandler);
mLoader.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS, onProgressHandler);
mLoader.load(mRequest);
function onCompleteHandler(e:Event):void {
game = e.currentTarget.content
game.alpha = 0;
}
function onProgressHandler(e:ProgressEvent):void {
loader.loadBar.setProgress(e.bytesLoaded, e.bytesTotal);
}
addEventListener(Event.ENTER_FRAME, function(e:Event):void {
if(game != null){
if(!added) {
addChild(game);
added = true;
}
if(game.alpha < 1) game.alpha += 0.1;
When I load my game console returns TypeError: Error #1009: Cannot access a property or method of a null object reference.
I turn on permit debugging in game and again load. Now console returns TypeError: Error #1009: Cannot access a property or method of a null object reference.
at main()[C: \Users\Lukasz\Desktop\Flash\rs\main.as:141];
So I checked 141 line and since 141 to 155 I have keyboard events.
stage.addEventListener(KeyboardEvent.KEY_UP, function(e:KeyboardEvent):void {
if(e.keyCode == 32 && moveAvailable) {
startEvent();
}else if(e.keyCode == 32) {
moveAvailable = true;
}
moveSpeed = 70;
});
stage.addEventListener(KeyboardEvent.KEY_DOWN, function(e:KeyboardEvent):void {
if(e.keyCode == 32) {
moveSpeed = 140
if(!startBtn.enb) moveAvailable = false;
}
});
When I get comment /**/ between this code game load correctly.
By the way I try this.parent and parent. instead of stage. but nothing changed :(
Someone have idea on this problem ?

Answer 1

You need check stage before use it
if (stage) {
addStageEvent();
} else {
this.addEventListener(Event.ADDED_TO_STAGE, addStageEvent);
}
function addStageEvent(e:Event = null):void {
//put the 141-155 line code here
}