Many issues

Hi, I'm a new developer and I am creating a custom game for my class. I have basic coding down and it works great. There are just a couple issues. When I run into a health power up, my health doesn't go up. It does, however, go down when I $$anonymous$$t an enemy. I also want my damage to the enemy to change depending on what power up bool is active in my player controller. However not$$anonymous$$ng happens. The weird t$$anonymous$$ng is, there are no errors. I also want my game to stop when. my health reaches zero, but not$$anonymous$$ng happens. It only says that there is a null reference in my game manager on line 25. If anyone can help, it will be much appreciated. Here are my scripts.

Player Health:

using System.Collections; using System.Collections.Generic; using UnityEngine; using UnityEngine.UI;

public class PlayerHealth : MonoBehaviour { public float health; public Slider slider; public float lifeUp = 30f; public float contactDamage = 5f;

 // Start is called before the first frame update
 void Start()
 {
     
 }

 // Update is called once per frame
 void Update()
 {
     slider.value = health;
 }

 void OnCollisionEnter(Collision obj)
 {
     if(obj.gameObject.tag == "Enemy")
     {
         health = health - contactDamage;
     }

     if(obj.gameObject.tag == "Life")
     {
         health = health + lifeUp;
         Debug.Log("Health Up");
     }
 }

}

Enemy Health:

using System.Collections; using System.Collections.Generic; using UnityEngine; using UnityEngine.UI;

public class EnemyHealth : MonoBehaviour { public float health; public Slider slider; private PlayerController playerController; public float currentDamage; public float speedDamage = 40f; public float strengthDamage = 50f; public float normalDamage = 20f;

 // Start is called before the first frame update
 void Start()
 {
     playerController = GetComponent<PlayerController>();
 }

 // Update is called once per frame
 void Update()
 {
     slider.value = health;

     if (health <= 0)
     {
         Destroy(gameObject);
     }
 }

 void OnCollisionEnter(Collision obj)
 {
     if (obj.gameObject.tag == "Player")
     {
         if (obj.gameObject.GetComponent<PlayerController>().hasPowerupStrength == true)
         {
             currentDamage = strengthDamage;
             Debug.Log("Damage Change");
         }
         else
         {
             currentDamage = normalDamage;
         }
         if (obj.gameObject.GetComponent<PlayerController>().hasPowerupSpeed == true)
         {
             currentDamage = speedDamage;
             Debug.Log("Damage Change");
         }
         else
         {
             currentDamage = normalDamage;
         }

         health = health - currentDamage;
     }
 }

}

Player Controller:

using System.Collections; using System.Collections.Generic; using UnityEngine; using TMPro;

public class PlayerController : MonoBehaviour { public float speedMove = 20; public float speedOrigin = 20; public float newspeed = 40; public float horizontalInput; public float verticalInput; public float xRange = 30; public float zBound = 30; public AudioClip wallHit; private AudioSource playerAudio; public bool hasPowerupSpeed; public bool hasPowerupStrength; public bool HasPowerupHealth; public GameObject PowerupSpeed; public GameObject PowerupStrength; public GameObject PowerupLife; private GameManager gameManager; public ParticleSystem fastParticle; public ParticleSystem normalParticle;

 // Start is called before the first frame update
 void Start()
 {
     fastParticle.Stop();
     gameManager = GameObject.Find("Game Manager").GetComponent<GameManager>();
     playerAudio = GetComponent<AudioSource>();
     PowerupStrength = GameObject.Find("PowerupStrength");
     PowerupSpeed = GameObject.Find("PowerupSpeed");
     PowerupLife = GameObject.Find("PowerupLife");
     normalParticle.Play();
 }

 // Update is called once per frame
 void Update()
 {
     //Get key input
     horizontalInput = Input.GetAxis("Horizontal");
     verticalInput = Input.GetAxis("Vertical");

     //Move the player around
     transform.Translate(Vector3.forward * Time.deltaTime * speedMove * verticalInput);
     transform.Translate(Vector3.right * Time.deltaTime * speedMove * horizontalInput);

     //Boundaries
     if (transform.position.x < -xRange)
     {
         transform.position = new Vector3(-xRange, transform.position.y, transform.position.z);
         playerAudio.PlayOneShot(wallHit, 1.0f);
     }

     if (transform.position.x > xRange)
     {
         transform.position = new Vector3(xRange, transform.position.y, transform.position.z);
         playerAudio.PlayOneShot(WallHit, 1.0f);
     }

     if (transform.position.z < -zBound)
     {
         transform.position = new Vector3(transform.position.x, transform.position.y, -zBound);
         playerAudio.PlayOneShot(WallHit, 1.0f);
     }

     if (transform.position.z > zBound)
     {
         transform.position = new Vector3(transform.position.x, transform.position.y, zBound);
         playerAudio.PlayOneShot(WallHit, 1.0f);
     }
 }

 private void OnTriggerEnter(Collider other)
 {

     //Destroy powerup if collected and start timer
     if (other.CompareTag("Speed"))
     {
        hasPowerupSpeed = true;
        Destroy(other.gameObject);
        StartCoroutine(SpeedPowerupCountdownRoutine());
     }

     //Destroy powerup if collected and start timer
     if (other.CompareTag("Strength"))
     {
           hasPowerupSpeed = true;
           Destroy(other.gameObject);
           StartCoroutine(StrengthPowerupCountdownRoutine());
     }

     //Destroy powerup if collected and start timer
     if (other.CompareTag("Life"))
     {
            HasPowerupHealth = true;
            Destroy(other.gameObject);
            
            HasPowerupHealth = false;
     }
 }

 IEnumerator SpeedPowerupCountdownRoutine()
 {
     //Countdown start and stop
     speedMove = newspeed;
     normalParticle.Stop();
     fastParticle.Play();
     yield return new WaitForSeconds(7);
     speedMove = speedOrigin;
     fastParticle.Stop();
     hasPowerupSpeed = false;
     normalParticle.Play();
 }

 IEnumerator StrengthPowerupCountdownRoutine()
 {
     //Countdown start and stop
     yield return new WaitForSeconds(7);
     hasPowerupStrength = false;
 }

}

Game Manger:

using System.Collections; using System.Collections.Generic; using UnityEngine; using UnityEngine.SceneManagement; using UnityEngine.UI; using TMPro;

public class GameManager : MonoBehaviour { public Button restartButton; public TextMeshProUGUI gameOverText; public bool isGameActive; private PlayerHealth playerhealth;

 // Start is called before the first frame update
 void Start()
 {
     isGameActive = true;
     playerhealth = GetComponent<PlayerHealth>();
 }

 // Update is called once per frame
 void Update()
 {
     if (playerhealth.health <= 0)
     {
         GameOver();
     }
 }

 public void GameOver()
 {
         gameOverText.gameObject.SetActive(true);
         isGameActive = false;
         restartButton.gameObject.SetActive(true);
 }

 public void RestartGame()
 {
     SceneManager.LoadScene(SceneManager.GetActiveScene().name);
 }

}

Enemy:

using System.Collections; using System.Collections.Generic; using UnityEngine; using UnityEngine.UI;

public class Enemy : MonoBehaviour { public float speed = 20.0f; private Rigidbody enemyRb; private GameObject player; public float xRange = 30; public float zBound = 30; public AudioClip WallHit; private AudioSource playerAudio; public ParticleSystem enemyParticle;

 // Start is called before the first frame update
 void Start()
 {
     //Variable meaning
     enemyRb = GetComponent<Rigidbody>();
     player = GameObject.Find("Player");
     playerAudio = GetComponent<AudioSource>();
     enemyParticle.Play();
 }

 // Update is called once per frame
 void Update()
 {
     //Find the player
     Vector3 lookDirection = (player.transform.position - transform.position).normalized;

     //Follow player
     enemyRb.AddForce(lookDirection * speed);

     //Boundaries1
     if (transform.position.x < -xRange)
     {
         transform.position = new Vector3(-xRange, transform.position.y, transform.position.z);
         playerAudio.PlayOneShot(WallHit, 1.0f);
     }
     if (transform.position.x > xRange)
     {
         transform.position = new Vector3(xRange, transform.position.y, transform.position.z);
         playerAudio.PlayOneShot(WallHit, 1.0f);
     }
     if (transform.position.z < -zBound)
     {
         transform.position = new Vector3(transform.position.x, transform.position.y, -zBound);
         playerAudio.PlayOneShot(WallHit, 1.0f);
     }
     if (transform.position.z > zBound)
     {
         transform.position = new Vector3(transform.position.x, transform.position.y, zBound);
         playerAudio.PlayOneShot(WallHit, 1.0f);
     }
 }

}