Getting a " NullReferenceException: Object reference not set to an instance of an object " - Space Shooter Tutorial 14 - Counting Points

Hello everyone,

As many other users, I am a first timer to both Unity and Programming, so please be patient with any ignorant questions that may come from me.

The Problem

• I keep getting an error that says "NullReferenceException: Object reference not set to an instance of an object" whenever I run the game.

• It is causing the game to detect collision, but does not destroy the objects or update the score.

• There is a particular line of code that is guilty of the error, but I cannot find a clear answer, even with my wonderful Google-fu fingers. The minute I comment-out this offending line, everything works fine.

Details:

• I am following a tutorial for the Space Shooter, and have landed on Step 14 : Counting Points

• I have gone over the tutorial 3 times, and for the life of me I cannot see what I am doing that is drastically different from the teacher.

• Please keep in mind that some of the concepts taught in this tutorial were from an older version of Unity. I currently run 5.5.2f1

• Essentially the script "DestroyByContact" code is attempting to grab a function from one game object (in this case from the game object and class GameController) and use it once an object is destroyed. I thought that I was referencing them accurately, but I guess I am wrong? (Or Unity has changed so drastically that this no longer applies?).

  I removed pieces of the code that have nothing to do with the problem at hand for the "GameController" Script. Fyi.

  ---

  HELP! c:

  ---

Debug Log

 NullReferenceException: Object reference not set to an instance of an object
 GameController.UpdateScore () (at Assets/Scripts/GameController.cs:81)
 GameController.AddScore (Int32 scoreValue) (at Assets/Scripts/GameController.cs:76)
 DestroyByContact.OnTriggerEnter (UnityEngine.Collider other) (at Assets/Scripts/DestroyByContact.cs:40)

 

DestroyByContact Code:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class DestroyByContact : MonoBehaviour 
 {
     public GameObject explosion; // Reference to grab a public gameObject for explosion- to then instantiate
     public GameObject playerExplosion; // Reference to grab a public gameObject for a Player explosion- to then instantiate
     public int scoreValue;
     private GameController gameController; //GameController is the class name we are referencing to. "gameController" is what we named the variable.
     private GameObject gameControllerObject;
 
         void Start ()
         {
         gameControllerObject = GameObject.FindWithTag ("GameController");
         if (gameControllerObject != null)
         {
             gameController = gameControllerObject.GetComponent <GameController>();
         }
         if (gameController == null)
         {
             Debug.Log ("Cannot find 'GameController' script");
         }
         }
 
     void OnTriggerEnter(Collider other) // A built in Unity method to handle collision triggers.
     {
         if (other.tag == "Boundary") // OnTriggerEnter, if tag is boundary, return
         {    
             return; //hands back control to the method that called it. This way, "Boundary" is never destroyed, and is persistently being ignored.
         }
 
         Instantiate (explosion, transform.position, transform.rotation); // instatiates explosion OnTriggerEnter
 
         if (other.tag == "Player")  // if tag is player, instatiate
         {
             Instantiate (playerExplosion, other.transform.position, other.transform.rotation);
         }
 
         gameController.AddScore (scoreValue);
         Destroy (gameObject); // destroys the shot on contact
         Destroy (other.gameObject); // destroys an object the laser collides with on contact
     }
 }

 

GameController Code

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 
 public class GameController : MonoBehaviour 
 {
     public GameObject hazard; // Public reference for a hazard GameObject, in this case the asteroid
     public Vector3 spawnValues; // Vector3 to set the Spawn parameters of the hazard/enemies
 
     public int hazardCount; // Public reference to set how many hazards you want per wave
 
     public float spawnWait; // This variable sets how much time to wait before the next gameObject spawn
     public float startWait; // This variable sets how much time before the first spawn starts
     public float waveWait; // This variable sets how much time to wait before the next Wave of spawns
 
     public Text scoreText;
     private int score;
 
     void Start()
     {
         StartCoroutine(SpawnWaves ());
         score = 0;
         UpdateScore ();
         scoreText = GetComponent<Text> ();
     }
 
     public void AddScore(int newScoreValue)
     {
         score += newScoreValue;
         UpdateScore ();
     }
 
     void UpdateScore()
     {
         scoreText.text = "Score: " + score;
     }
 }