Null Reference Exception ? :/

 UnityEngine.GameObject.GetComponent<Player1> () (at C:/BuildAgent/work/7535de4ca26c26ac/Runtime/ExportGenerated/Editor/UnityEngineGameObject.cs:27)
 xa.Start () (at Assets/Scripts/xa.cs:30)

I get this error when i go to run my game

Here is my code

 using UnityEngine;
 using System.Collections;
 
     public class xa : MonoBehaviour 
     {
         public static Ball ball;
         public static AudioManager audioManager;
         public static ScoreManager scoreManager;
         
         public static Player1 player1;
         public static Player2 player2;
         //public static Player3 player3;
         //public static Player4 player4;
         
         public static bool gameOver = false;
         
         // set to false if game is configured for CTF
         public static bool letsPlayKeepaway = false; 
         
         // layers
         public const int Team1Goal = 9;
         public const int Team2Goal = 10;
         
         void Start()
         {
             // cache these so they can be accessed by other scripts
             ball = GameObject.FindWithTag("Ball").GetComponent<Ball>();
             scoreManager = gameObject.GetComponent<ScoreManager>();
             audioManager = gameObject.GetComponent<AudioManager>();
             player1 = GameObject.Find("Player1").GetComponent<Player1>();
             player2 = GameObject.Find("Player2").GetComponent<Player2>();
             //player3 = GameObject.Find("Player3").GetComponent<Player3>();
             //player4 = GameObject.Find("Player4").GetComponent<Player4>();
         }
     }

I dont know what i need to change or set ? If anyone has some advice?