Removing MC from array AS3 - actionscript-3

Question

I am having a problem removing a MovieClip from an array.
I am getting this error :
TypeError: Error #1009: Cannot access a property or method of a null object reference.
at Spiker/loop()".
The spike (Spiker) is getting removed, but the error still annoys me.. Any idea how to fix this?
Here is my code :
package {
import flash.display.MovieClip;
import flash.events.Event;
public class Spiker extends MovieClip {
public var spikeDirection:int = 1;
private var removed = false;
public function Spiker() {
// constructor code
trace("Spiker added");
addEventListener(Event.ENTER_FRAME, loop);
}
private function loop (evt){
this.x += spikeDirection * 10;
for(var i:int = 0; i < this["parent"].enemyList.length; i++){
if(removed == false){
if(this["parent"].enemyList[i].hitTestObject(this)){
trace("Spikerhit");
removed = true;
remove(evt);
}
}
}
}
public function remove (evt){
removeEventListener(Event.ENTER_FRAME, loop);
this["parent"].removeChild(this);
}
}

Answer 1

Your problem is coming from your for loop, this line exactly :
for(var i:int = 0; i < this["parent"].enemyList.length; i++){
because when your current object has touched an enemy it is removed from its parent, and for the next iteration of the for loop (if there is one), this["parent"] is null and that's why that error is fired as the for loop is verifying every iteration the conditional statement that determines when the looping ends (this["parent"].enemyList.length in your case).
To avoid that, you can use a variable, for example, to store the number of enemies to be used in the for loop.
You can also use the break statement inside your for loop after removing your object to exit that loop.
Hope that can help.