Actionscript 3: Trouble with removing child from parent - actionscript-3

Question

I am coding for learning purposes and have encountered an apparently unfixable problem.
I will first introduce you to my code.
This is a function in my Main class
public function confirm_route(evt:MouseEvent):void
{
var route = new Route(this, Airport.return_ROUTE);
Airport.return_ROUTE = new Array();
}
"Airport.return_ROUTE" is simply an array and its origin is not really relevant for the problem. In the Main class I'm also declaring my background var, and putting it as a public static var. Since I need to access this background from two other classes, I don't see another option but to declare it as that, even though I think it is not ideal. I will come back to this later in the explaination.
My Route class is dynamically creating new flights on the screen, hence the name. This is based on the Airport.return_ROUTE array. I need these flights to be added as childs to the background, which was created at Main class as mentioned. This is also why I added "this" as a parameter when calling the route function.
this.myparent = pMyParent;
I use the line above to be able to refer to the main instance. Since the Route instance is no movieclip I guess this is the only way to be able to refer to this.
As earlier mentioned the Route instance dynamically creats new_flights.
new_flight = new Flight(infoarray);
myparent.background_mc.addChild(new_flight);
This obviously is purposed to add the new_flight to the background movieclip.
Let us then look at the Flight class, since this is where the problem occurs.
Due to my game concept I need the new_flight to be removed once it reaches a certain point on the background movieclip.
This function is intended to do that job:
private function deleteThis():void
{
this.parent.removeChild(this)
}
This returns TypeError: Error #1009: Cannot access a property or method of a null object reference.
I really don't understand how to solve this differently.
EDIT: As requested, I will post my Route class.
package
{
import flash.events.TimerEvent;
import flash.utils.Timer;
import flash.display.MovieClip;
import flash.events.Event;
import flash.events.EventDispatcher;
import Main;
public class Route extends Main
{
public var income:Number;
public var routePoints:Array;
private var routeTimer:Timer;
private var new_flight:Flight;
// ------------
private var myparent:Main;
public function Route(route_array:Array, pMyParent)
{
this.myparent = pMyParent;
this.routePoints = route_array;
routeTimer = new Timer(2000);// 2 second
routeTimer.addEventListener(TimerEvent.TIMER, route_function);
routeTimer.start();
}
private function route_function(event:TimerEvent):void
{
for (var counter:uint = 0; counter < routePoints.length - 1; counter ++)
{
trace("Coords: ", routePoints[counter][0],routePoints[counter][1],routePoints[counter + 1][0],routePoints[counter + 1][1]);
new_flight = new Flight(myparent, routePoints[counter][0],routePoints[counter][1],routePoints[counter + 1][0],routePoints[counter + 1][1]);
myparent.bg_image.addChild(new_flight);
var checkTimer:Timer = new Timer(15);// 1 second
checkTimer.addEventListener(TimerEvent.TIMER, check_function);
checkTimer.start();
function check_function(event:TimerEvent):void
{
if (new_flight.finished = true)
{
checkTimer.stop();
}
}
}
}
}
}
EDIT 2: Posting Flight class aswell
package
{
import flash.display.MovieClip;
import flash.display.Sprite;
import flash.events.MouseEvent;
import flash.events.Event;
import flash.display.SimpleButton;
import flash.display.Stage;
import flash.events.TimerEvent;
import flash.utils.Timer;
import fl.controls.Button;
import flash.display.DisplayObject;
public class Flight extends MovieClip
{
public static var speed:uint = 1
public var finished:Boolean = false;
protected var absvector:Number;
protected var vector:Array;
protected var myTimer:Timer;
//protected var parentContainer:MovieClip;
protected var utgangspunkt_x;
protected var utgangspunkt_y;
protected var destinasjon_x;
protected var destinasjon_y;
protected var vector_x;
protected var vector_y;
private var myparent:Main
public function Flight(pMyParent, utgangspunkt_x, utgangspunkt_y, destinasjon_x, destinasjon_y):void
{
addEventListener(Event.ADDED_TO_STAGE, init);
this.myparent = pMyParent;
this.utgangspunkt_x = utgangspunkt_x;
this.utgangspunkt_y = utgangspunkt_y;
this.x = utgangspunkt_x;
this.y = utgangspunkt_y;
this.destinasjon_x = destinasjon_x + 10;
this.destinasjon_y = destinasjon_y + 10;
this.vector_x = Math.abs(this.destinasjon_x-this.utgangspunkt_x);
this.vector_y = Math.abs(this.destinasjon_y-this.utgangspunkt_y);
this.height = 20;
this.width = 20;
}
public function init(evt:Event):void
{
removeEventListener(Event.ADDED_TO_STAGE, init);
trace(this.parent)
trace("---------------------------------------------------")
if (utgangspunkt_x < destinasjon_x)
{
this.rotation = -(Math.atan((utgangspunkt_y-destinasjon_y)/(destinasjon_x-utgangspunkt_x)))/(Math.PI)*180;
}
else
{
this.rotation = 180-(Math.atan((utgangspunkt_y-destinasjon_y)/(destinasjon_x-utgangspunkt_x)))/(Math.PI)*180;
}
absvector = Math.sqrt(Math.pow((destinasjon_x - utgangspunkt_x),2) + Math.pow((utgangspunkt_y - destinasjon_y),2));
vector = [(destinasjon_x - utgangspunkt_x) / absvector,(utgangspunkt_y - destinasjon_y) / absvector];
stage.addEventListener(Event.ENTER_FRAME, movement)
}
private function movement(evt:Event):void
{
if (this.vector_x > this.vector_y)
{
if (destinasjon_x>utgangspunkt_x)
{
if (this.x < destinasjon_x)
{
this.x += speed*vector[0];
this.y -= speed*vector[1];
}
else
{
deleteThis()
}
}
else if (destinasjon_x<utgangspunkt_x)
{
if (this.x > destinasjon_x)
{
this.x += speed*vector[0];
this.y -= speed*vector[1];
}
else
{
deleteThis()
}
}
}
else
{
if (destinasjon_y>utgangspunkt_y)
{
if (this.y < destinasjon_y)
{
this.x += speed*vector[0];
this.y -= speed*vector[1];
}
else
{
deleteThis()
}
}
else if (destinasjon_y<utgangspunkt_y)
{
if (this.y > destinasjon_y)
{
this.x += speed*vector[ 0];
this.y -= speed*vector[1];
}
else
{
deleteThis()
}
}
}
}
private function deleteThis():void
{
finished = true;
this.parent.removeChild(this)
}
}
}

Answer 1

I suspect your deleteThis method is called more than once. That would explain why you have [object Image] and then nothing...
Is this method called by some kind of event? If that is the case, make sure this event is not triggered more than once.