Object reference not set to an instance of an Object Error

So i am doing this script, and get this error ,help me please;

here is the script

 using UnityEngine;
 using System.Collections;
 using UnityEngine.SceneManagement;
 using System.Collections.Generic;
 using UnityEngine.UI;
 
 
 
 using Hashtable = ExitGames.Client.Photon.Hashtable;
 
 public class RigidbodyFPSWalker : MonoBehaviour
 {
 
 
     public float speed = 10.0f;
     public float gravity = 10.0f;
     public float maxVelocityChange = 10.0f;
     public bool canJump = true;
     public float jumpHeight = 2.0f;
     private bool grounded = false;
     public PhotonView name;
 
     public string theKiller = "";
     public string killerWep = "";
 
     public GameObject me;
     public GameObject graphics;
     public GameObject ragDoll;
 
     public int health = 100;
 
     public GameObject fpsCam;
 
     public bool isPause = false;
 
     public AudioSource sound1;
 
     public AudioClip soundClip;
 
     private GUIStyle guiStyle = new GUIStyle();
 
     //kills
     public int kills = 0;
     //mortes
     public int deaths = 0;
 
 
     void Start()
     {
 
 
         GetComponent<Rigidbody>().freezeRotation = true;
         GetComponent<Rigidbody>().useGravity = false;
         name.RPC("updateName", PhotonTargets.AllBuffered, PhotonNetwork.playerName, health);
         gameObject.name = PhotonNetwork.playerName;
 
 
 
     }
 
 
 
     void FixedUpdate()
     {
 
         kills = PlayerPrefs.GetInt("kills");
         deaths = PlayerPrefs.GetInt("deaths");
 
 
         if (grounded)
         {
 
             // Calculate how fast we should be moving
             Vector3 targetVelocity = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical"));
             targetVelocity = transform.TransformDirection(targetVelocity);
             targetVelocity *= speed;
 
             // Apply a force that attempts to reach our target velocity
             Vector3 velocity = GetComponent<Rigidbody>().velocity;
             Vector3 velocityChange = (targetVelocity - velocity);
             velocityChange.x = Mathf.Clamp(velocityChange.x, -maxVelocityChange, maxVelocityChange);
             velocityChange.z = Mathf.Clamp(velocityChange.z, -maxVelocityChange, maxVelocityChange);
             velocityChange.y = 0;
             GetComponent<Rigidbody>().AddForce(velocityChange, ForceMode.VelocityChange);
 
             // Jump
             if (canJump && Input.GetButton("Jump"))
             {
                 GetComponent<Rigidbody>().velocity = new Vector3(velocity.x, CalculateJumpVerticalSpeed(), velocity.z);
             }
 
 
         }
 
         if (Input.GetKeyDown(KeyCode.Q))
         {
             isPause = true;
 
         }
         if (Input.GetKeyUp(KeyCode.Q))
         {
             isPause = false;
         }
 
 
         if (Input.GetKey(KeyCode.Escape))
         {
             Application.Quit();
 
         }
 
         // We apply gravity manually for more tuning control
         GetComponent<Rigidbody>().AddForce(new Vector3(0, -gravity * GetComponent<Rigidbody>().mass, 0));
 
         grounded = false;
 
         if (health <= 0)
         {
             GetComponent<PhotonView>().RPC("DIE", PhotonTargets.AllBuffered, null);
         }
 
     }
 
 
 
     void OnCollisionStay()
     {
         grounded = true;
     }
 
     float CalculateJumpVerticalSpeed()
     {
         // From the jump height and gravity we deduce the upwards speed 
         // for the character to reach at the apex.
         return Mathf.Sqrt(2 * jumpHeight * gravity);
     }
 
     /*
         void OnGUIStop(){
             GUI.color = Color.red;
             GUI.Box (new Rect (100, 10, 100, 30), "HP | " + health);
 
             if (isPause) {
                 GUILayout.BeginArea (new Rect(Screen.width/2 - 250, Screen.height/2 - 250, 500,500));
 
                 foreach (var teamName in PunTeams.PlayersPerTeam.Keys)
                 {
                     GUILayout.Label("Team: " + teamName.ToString());
                     List<PhotonPlayer> teamPlayers = PunTeams.PlayersPerTeam[teamName];
                     foreach (PhotonPlayer player in teamPlayers)
                     {
                         GUILayout.Label("  " + player.ToStringFull() + " Score: " + player.GetScore());
                     }
                 }
                 GUILayout.EndArea ();
             }
         }
     */
 
 
 
 
     public void getClip(AudioClip soundToRecieve)
     {
         Debug.Log(soundToRecieve.name);
         soundClip = soundToRecieve;
     }
 
 
 
     [PunRPC]
     public void applyDamage(int dmg, string killerName, string wepName)
     {
         health = health - dmg;
         name.RPC("updateName", PhotonTargets.AllBuffered, PhotonNetwork.playerName, health);
         theKiller = killerName;
         killerWep = wepName;
         Debug.Log("hit!" + health);
     }
 
 
 
     [PunRPC]
     public void DIE()
     {
         if (GetComponent<PhotonView>().isMine)
         {
 
             PhotonNetwork.Destroy(me);
             Destroy(me);
 
             ragDoll = PhotonNetwork.Instantiate(ragDoll.name, transform.position, transform.rotation, 0);
             ragDoll.GetComponent<Rigidbody>().AddForce(transform.forward, ForceMode.Force);
             Destroy(ragDoll, 1);
 
             PlayerPrefs.SetInt("deaths", deaths + 1);
 
             GameObject.Find("_ROOM").GetComponent<lobbyManager>().OnJoinedRoom();
             GameObject.Find("_NetworkScripts").GetComponent<PhotonView>().RPC("addFeed", PhotonTargets.All, theKiller + " [" + killerWep + "] " + PhotonNetwork.playerName);
 
 
             /*
             foreach (var teamName in PunTeams.PlayersPerTeam.Keys) {
 
                 List<PhotonPlayer> teamPlayers = PunTeams.PlayersPerTeam [PunTeams.Team.red];
                 foreach (PhotonPlayer player in teamPlayers) {
                     GameObject.Find ("_NetworkScripts").GetComponent<PhotonView>().RPC ("addFeed", PhotonTargets.All, theKiller + " [" + killerWep + "] " + PhotonNetwork.playerName);
                     GameObject killer2 = GameObject.Find (theKiller);
                     killer2.GetComponent<PhotonView>().RPC ("addKill", PhotonTargets.AllBuffered, null);
                     killer2.GetComponent<PhotonView>().RPC ("exitTrig", PhotonTargets.AllBuffered, null);
                     GameObject.Find ("_ROOM").GetComponent<lobbyManager> ().teamRed ();
                     return;
                 }
 
             }
 */
 
             /*
             foreach (var teamName2 in PunTeams.PlayersPerTeam.Keys) {
 
                 List<PhotonPlayer> teamPlayers2 = PunTeams.PlayersPerTeam[PunTeams.Team.blue];
                 foreach (PhotonPlayer player2 in teamPlayers2) {
                     GameObject.Find ("_NetworkScripts").GetComponent<PhotonView>().RPC ("addFeed", PhotonTargets.All, theKiller + " [" + killerWep + "] " + PhotonNetwork.playerName);
                     GameObject.Find ("_ROOM").GetComponent<lobbyManager> ().teamBlue ();
 
                 }
             }
 */
             GameObject killer2 = GameObject.Find(theKiller);
             print("gameObejct " + killer2);
             killer2.GetComponent<PhotonView>().RPC("addKill", PhotonTargets.AllBuffered, null);
             killer2.GetComponent<PhotonView>().RPC("exitTrig", PhotonTargets.AllBuffered, null);
 
         }
 
 
     }
 
     [PunRPC]
     public void addKill()
     {
 
         PlayerPrefs.SetInt("kills", kills + 1);
 
     }
 
     void OnTriggerEnter(Collider other)
     {
 
         if (other.tag == "life")
         {
             int upgrade_health = 50;
             health += upgrade_health;
         }
     }
 
 
 
     public AudioClip[] sounds;
 
 
     [PunRPC]
     public void playSound()
     {
         Debug.Log("Sound: " + soundClip.name);
         sound1.PlayOneShot(soundClip);
     }
 
     void OnGUI()
     {
         guiStyle.fontSize = 40;
         GUI.color = Color.green;
         GUI.Label(new Rect(200, 850, 150, 30), "" + health, guiStyle);
 
         if (isPause)
         {
             GUILayout.BeginArea(new Rect(Screen.width / 2 - 250, Screen.height / 2 - 250, 500, 500));
             GUILayout.Box("Score:" + "\nKills: " + kills + " / " + "Deaths: " + deaths);
             GUILayout.Box("Players:    Name         K/D   ");
             foreach (PhotonPlayer pl in PhotonNetwork.playerList)
             {
                 GUILayout.Box(pl.name + " | " + pl.GetScore());
             }
             GUILayout.EndArea();
         }
 
     }
 
 }