Flash Game Actionscript-3 Output Error #1009 - actionscript-3

Question

I am making my own game using Actionscript 3 for coding in Flash. The game is about a Runner Character just like Super Mario and Stickyman, who just run, jump, dies.. and so on..
After being very organized by dividing each window of the game in a different Scene, I was still having the problem of executing the piece of code "gotoAndStop()".. That's why I decided to make it much simple by using only one Scene, but each wind of the game in a different frame in the Main Timeline. So I worked on the root, but still getting the same problem that stuck in a white screen!
Anyways, one of the main problem that I am facing here is the Error #1009. Even when I tried to read other topics with the same issue but I didn't find the answer that suites my case.
This is the Error:
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at HR4_fla::MainTimeline/movePlayer()
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at Apple/update()
Here is the Code:
import flash.events.KeyboardEvent;
import flash.events.Event;
import flash.display.MovieClip;
import flash.geom.Rectangle;
stop();
var KeyThatIsPressed:uint;
var rightKeyIsDown:Boolean = false;
var leftKeyIsDown:Boolean = false;
var upKeyIsDown:Boolean = false;
var downKeyIsDown:Boolean = false;
var score:int = 0;
var lives:int = 3;
player_mc.health = 100;
player_mc.dead = false;
//var TouchRestartBox:Boolean = false;
var playerSpeed:Number = 8;
var gravity:Number = 2;
var yVelocity:Number = 0;
var canJump:Boolean = false;
var canDoubleJump: Boolean = false;
//var appleCount:int;
stage.addEventListener(KeyboardEvent.KEY_DOWN, PressAKey);
stage.addEventListener(KeyboardEvent.KEY_UP, ReleaseAKey);
stage.addEventListener(Event.ENTER_FRAME, cameraFollowCharacter);
function cameraFollowCharacter(event:Event):void
{
scrollRect = new Rectangle(player_mc.x - stage.stageWidth/2, player_mc.y - stage.stageHeight/2, stage.stageWidth, stage.stageHeight);
}
//PressKey function here
function PressAKey(event:KeyboardEvent):void
{
if(event.keyCode == Keyboard.RIGHT)
{
rightKeyIsDown = true;
}
if(event.keyCode == Keyboard.LEFT)
{
leftKeyIsDown = true;
}
if(event.keyCode == Keyboard.UP)
{
upKeyIsDown = true;
}
if(event.keyCode == Keyboard.DOWN)
{
downKeyIsDown = true;
}
}
//ReleaseKey function here
function ReleaseAKey(event:KeyboardEvent):void
{
if(event.keyCode == Keyboard.RIGHT)
{
rightKeyIsDown = false;
}
if(event.keyCode == Keyboard.LEFT)
{
leftKeyIsDown = false;
}
if(event.keyCode == Keyboard.UP)
{
upKeyIsDown = false;
}
if(event.keyCode == Keyboard.DOWN)
{
downKeyIsDown = false;
}
}
//stage.addEventListener(Event.ENTER_FRAME, GameOver);
stage.addEventListener(Event.ENTER_FRAME, movePlayer);
function movePlayer(event:Event):void
{
if(!rightKeyIsDown && !leftKeyIsDown && !upKeyIsDown)
{
player_mc.gotoAndStop(1);
}
if(rightKeyIsDown)
{
player_mc.gotoAndStop(2);
player_mc.x+= playerSpeed;
player_mc.scaleX = 0.59;
}
if(leftKeyIsDown)
{
player_mc.gotoAndStop(2);
player_mc.x-= playerSpeed;
player_mc.scaleX = -0.59;
}
if(upKeyIsDown && canJump)
{
player_mc.gotoAndStop(3);
yVelocity = -15;
canJump = false;
canDoubleJump = true;
}
if(upKeyIsDown && canDoubleJump && yVelocity > -2)
{
yVelocity = -13;
canDoubleJump = false;
}
yVelocity +=gravity;
if(!floor_mc.hitTestPoint(player_mc.x,player_mc.y, true))
{
player_mc.y+=yVelocity;
}
if(yVelocity > 20)
{
yVelocity =20;
}
for(var i:int=0; i<10; i++)
{
if(floor_mc.hitTestPoint(player_mc.x, player_mc.y, true))
{
player_mc.y--;
yVelocity = 0;
canJump = true;
}
}
for(var j:int=0; j<=2; j++)
{
if(rb.hitTestPoint(player_mc.x, player_mc.y, true))
{
player_mc.x = -1703.35;
player_mc.y = 322.1;
player_mc.scaleX = 0.59;
lives = lives - 1;
}
if(lives == 0)
{
// GameOver();
// remove all the event listeners
// stage.removeEventListener(Event.ENTER_FRAME, GameOver);
stage.removeEventListener(Event.ENTER_FRAME, movePlayer);
stage.removeEventListener(KeyboardEvent.KEY_DOWN, PressAKey);
stage.removeEventListener(KeyboardEvent.KEY_UP, ReleaseAKey);
stage.removeEventListener(Event.ENTER_FRAME, cameraFollowCharacter);
gotoAndStop(124);
//(root as MovieClip).gotoAndStop(124);
}
}
// appleCount_txt.text = "Apples:" + appleCount;
}
/*function GameOver()
{
// lives = 3;
// remove all the event listeners
stage.removeEventListener(Event.ENTER_FRAME, GameOver);
stage.removeEventListener(Event.ENTER_FRAME, movePlayer);
stage.removeEventListener(KeyboardEvent.KEY_DOWN, PressAKey);
stage.removeEventListener(KeyboardEvent.KEY_UP, ReleaseAKey);
stage.removeEventListener(Event.ENTER_FRAME, cameraFollowCharacter);
// player_mc.stop();
gotoAndStop(1); // this has your "dead" screen on it.
}*/
Can anyone help me solving this problem please?
Thanks

Answer 1

There's a listener still getting executed after the frame change. In that handler, an object is referenced that does not exist on that frame and is thus null.
Changing frames only provides visual changes, not necessarily a complete change of state.