Every time I relaunch my game I Object reference not set to an instance of an object

Questions & Answers
1

My AI script always gets a error when I relaunch it or build it
I have to delete the way point script on my nodes and add them back for it to work
I don’t know why this happens.
Waypoints Script:
using UnityEngine;

public class Waypoints : MonoBehaviour {

	public static Transform[] points;

	void Start ()
	{
		points = new Transform[transform.childCount];
		for (int i = 0; i < points.Length; i++)
		{
			points *= transform.GetChild(i);*

  •  }*
  • }*

}
Enemy Script
using System;
using UnityEngine;

public class Enemy : MonoBehaviour {
public GameObject deathEffect;
public GameObject BeingShot;
public float speed = 10f;
public int health = 500;
public Transform enemyObj;

  • private Transform target;*

  • private int wavepointIndex = 0;*

  • void Start ()*

  • {*

  •  target = Waypoints.points[0];*

}

  • void Update ()*
  • {*
  •  Vector3 dir = target.position - enemyObj.position;*

_ transform.Translate(dir.normalized * speed * Time.deltaTime, Space.World);_

  •  if (Vector3.Distance(enemyObj.position, target.position) <= 50f)*

  •  {*

  •  	GetNextWaypoint();*

  •  }*
  • }*

public void takeDamage(int ammount)
{
GameObject effect = (GameObject)Instantiate(BeingShot, transform.position, Quaternion.identity);
Destroy(effect, .3f);
Debug.Log(“Has taken damage”);
health -= ammount;

if (health <= 0)
{

death();

}

}

void death()
{
GameObject effect = (GameObject)Instantiate(deathEffect, transform.position, Quaternion.identity);
Destroy(effect, 5f);
Destroy(gameObject);
}

void GetNextWaypoint()

  • {*
  •  if (wavepointIndex >= Waypoints.points.Length - 1)*

  •  {*

endpath();

  •  	return;*

  •  }*

  •  wavepointIndex++;*

  •  target = Waypoints.points[wavepointIndex];*

  • }*

public void endpath()
{
Playerstats.Lives–;
Debug.Log(“U should work :/”);
Destroy(gameObject);
}
}

2

Hi @lonelycamper ,

That looks to me a race condition. If the AI scripts execute before the Waypoints you’ll hit that issue. The easiest solution is to initialize the Waypoint script in the Awake:

 public class Waypoints : MonoBehaviour {
 
     public static Transform[] points;
 
     void Awake()
     {
         points = new Transform[transform.childCount];
         for (int i = 0; i < points.Length; i++)
         {
             points *= transform.GetChild(i);*

}
}
}
This way you won’t hit that problem, and the children transform are there even if they are not initialized yet, so you can safely retrieve their reference.

3

Try lazy load it:

    private Transform[] _points;
    public static Transform[] points
    {
        get
        {
            if (_points != null) return _points;
            _points = new Transform[transform.childCount];
            for (int i = 0; i < _points.Length; i++)
            {
                _points *= transform.GetChild(i);*

}
return _points;
}
}
Could be that you have to reference the MonoBehaviour before actually not sure
Waypoints waypoints = GetComponent();
if the waypoints script is also on the enemy. Then you can use it like waypoints.points[0]