destroying a unit and removing it from a list

Hey guys,
Im making a simple rts game and when I have my player unit destroy an enemy unit is keeps returning erros and breaks the game. I do not know the right way to go about this. I have lists detect the enemies on the field. The player unit finds the closest one and attacks it. WHen its dead i use destroy object and some null exceptions but im still getting errors. Could you help? Thanks,

public void Start () {

	StartCoroutine (CountEnemies()); //counts the amount of enemies that have been spawned

	StartCoroutine (DetectEnemies()); //this detects if the enemies are in range, and then moves to them


public void FixedUpdate () { //runs update at a fixed fps

	//attacking the enemy

	if (playerAttacking == true) {
		GameObject EnemyObject = EnemyList[minDistanceIndex]; //creates an object for that specific player unit							

		if(EnemyObject != null){

		Enemy EnemyHealthDecrease = EnemyObject.GetComponent<Enemy> ();
		//	print (Time.time);
			Debug.Log ("-----------------------the player hit an enemy unit!");//simple test for enemy attack

			print("the units health is at" +;
			coolDown = Time.time + attackRate;

IEnumerator CountEnemies(){ //this is where the game detects the # enemies that have been spawned
		while (true) {

		GameObject[] EnemyArray = GameObject.FindGameObjectsWithTag("Enemy"); //creates an array populated with the enemies
		for(int i=0 ; i<EnemyArray.Length; i++){ //iterates through the array and adds all objects to the list

_ EnemyList.Insert(i, EnemyArray*); //adding to the list*_
* }*
* }*
* yield return new WaitForSeconds(1f);*
* }*
* }*
IEnumerator DetectEnemies(){
* while (true) {*

* if(playerAttacking==false){*
* for(int i=0; i< EnemyList.Count; i++){*
_ if(EnemyList !=null){
float distance = Vector3.Distance (transform.position, EnemyList*.transform.position); //finds distance between enemy and player*
* DistanceToEnemyList.Insert(i,distance); //inserts the distance values at the indicies*
* SortedDistanceToEnemyList.Insert(i,distance); //this is the same as distancelist but will be sorted*_

* SortedDistanceToEnemyList.Sort();//sorts the list in ascending order*
* //min distance is the first index of sorted list…*
* }*
* }*
* if(SortedDistanceToEnemyList[0]!=null){*
* minDistanceIndex = DistanceToEnemyList.IndexOf(SortedDistanceToEnemyList[0]);*
* }*
* }*
* //this should give the index of the smallest distance*
* if (DistanceToEnemyList[minDistanceIndex] <= 10 && minDistanceIndex!=null) { //if the distance is less than 10 between player unit and enemy unit *
* //index out of range?*
* GameObject enemyObject = EnemyList[minDistanceIndex]; //creates an object for that specific player unit *
* if(enemyObject!=null){*
* AstarAIEnemy enemyObjectDetection = enemyObject.GetComponent (); //gets astarai code for that unit*
* targetPosition = enemyObjectDetection.transform.position; //sets the enemy position to the pos of the player unit*

* float distanceToTargetPos = Vector3.Distance (targetPosition, transform.position); //finds distance between the two units*
* if (distanceToTargetPos > 2 && distanceToTargetPos<=10) {*
* playerAttacking=false;//this makes it so the enemy stops attacking when player is far away*
* seeker.StartPath (transform.position, targetPosition, OnPathComplete); //if distance is more than 3 than travel towards its destination*
* }*
* if (distanceToTargetPos<2){*
* playerAttacking=true;*
* }*
* }*
* }//end of if distance < X*
* // Debug.Log(“Check Enemy detection”);*
* //DistanceToEnemyList.Clear();*
* //SortedDistanceToEnemyList.Clear();*
* yield return new WaitForSeconds(1f);*

* }*
* }*

What’s the bug that you have encountered? like killing an enemy doesn’t kill it, or it spawns more, or the enemy respawns?
I would have moved the destroying code to the enemy(die when life<0) though, since the enemy array is automatically updated each frame, so the player don’t have to do focus on how the enemy dies.

I figured it out. Basically when an object was destroyed, it was removed from the game so the EnemyArray wasnt detecting it anymore. It was still in the other lists though. I just made it so the other lists are cleared when the enemy is destroyed, and moved around some playerAttacking bools. Thanks for your help,