Object reference not set to an instance of an object

I get this error whenever I press 5: NullReferenceException:

Object reference not set to an instance of an object WarriorSpin.Update () (at Assets/Scripts/SpellsAndAbilities/Warrior/WarriorSpin.cs:30)

I have checked to make sure everything is the way it is supposed to be but it still doesn't work.

Here is my code:

 using UnityEngine;
 using UnityEngine.UI;
 using System.Collections;
 
 public class WarriorSpin : MonoBehaviour {
 
     public GameObject player;
     
     public float coolDown;
     
     PlayerScript ps;
 
     public GameObject canvas;
     
     public GameObject errorMessageArea;
     
     void Start () {
         player = gameObject;
         
         ps = player.GetComponent<PlayerScript> ();
 
         canvas = GameObject.Find ("HudCanvas");
         
         errorMessageArea = GameObject.Find ("ErrorMessageArea");
     }
     
     void Update () {
         if (Input.GetButtonDown ("5")) {
             if (coolDown <= 0) {
                 if (ps.mana > 50) {
                     ps.isWarriorSpin = true;
                     coolDown = 30;
                     ps.mana -= 50;
                 } else {
                     GameObject notEnoughManaObject = Instantiate (ps.notEnoughMana, errorMessageArea.transform.position, errorMessageArea.transform.rotation) as GameObject;
                     notEnoughManaObject.transform.SetParent (canvas.gameObject.transform);
                 }
             } else {
                 GameObject notReadyYetObject = Instantiate (ps.notReadyYet, errorMessageArea.transform.position, errorMessageArea.transform.rotation) as GameObject;
                 notReadyYetObject.transform.SetParent (canvas.gameObject.transform);
             }
         }
 
         if (GetComponent<Text> () != null && coolDown > 1) {
             GetComponent<Text> ().text = "" + coolDown.ToString ("0");
         }
 
         if (GetComponent<Text> () != null && coolDown > 0 && coolDown <= 1) {
             GetComponent<Text> ().text = "" + coolDown.ToString ("F1");
         }
 
         if (GetComponent<Text> () != null && coolDown <= 0) {
             GetComponent<Text> ().text = "";
         }
         
         coolDown -= Time.deltaTime;
     }
 }