NullReferenceException

Hey everyone, recently I have been getting these two Errors and I don't know how to solve them,

 ArgumentOutOfRangeException: Argument is out of range.
 Parameter name: index
 System.Collections.Generic.List`1[UnityEngine.Mesh].get_Item (Int32 index) (at /Applications/buildAgent/work/3df08680c6f85295/mcs/class/corlib/System.Collections.Generic/List.cs:633)
 Main.BuildData ()
 Main.OnEnable ()
 UnityEngine.Network:Instantiate(Object, Vector3, Quaternion, Int32)
 MultiplayerManager:ClientAddPlayerToList(String, NetworkPlayer) (at Assets/Scripts/MultiplayerManager.cs:83)
 UnityEngine.NetworkView:RPC(String, RPCMode, Object[])
 MultiplayerManager:ServerPlayerJoinRequest(String, NetworkPlayer) (at Assets/Scripts/MultiplayerManager.cs:68)
 MultiplayerManager:OnServerInitialized() (at Assets/Scripts/MultiplayerManager.cs:44)
 UnityEngine.Network:InitializeServer(Int32, Int32, Boolean)
 MultiplayerManager:StartServer(String, String, Int32) (at Assets/Scripts/MultiplayerManager.cs:38)
 MenuManager:Main_Host() (at Assets/Scripts/MenuManager.cs:94)
 MenuManager:OnGUI() (at Assets/Scripts/MenuManager.cs:33) 

and

 NullReferenceException
 UnityEngine.Mesh.get_bounds () (at C:/BuildAgent/work/a0f11f3559d72c6d/Runtime/ExportGenerated/Editor/Grap$$anonymous$$cs.cs:971)
 Main.BuildData ()
 Main.OnEnable ()
 UnityEngine.Network:Instantiate(Object, Vector3, Quaternion, Int32)
 MultiplayerManager:ClientAddPlayerToList(String, NetworkPlayer) (at Assets/Scripts/MultiplayerManager.cs:83)
 UnityEngine.NetworkView:RPC(String, RPCMode, Object[])
 MultiplayerManager:ServerPlayerJoinRequest(String, NetworkPlayer) (at Assets/Scripts/MultiplayerManager.cs:68)
 MultiplayerManager:OnServerInitialized() (at Assets/Scripts/MultiplayerManager.cs:44)
 UnityEngine.Network:InitializeServer(Int32, Int32, Boolean)
 MultiplayerManager:StartServer(String, String, Int32) (at Assets/Scripts/MultiplayerManager.cs:38)
 MenuManager:Main_Host() (at Assets/Scripts/MenuManager.cs:94)
 MenuManager:OnGUI() (at Assets/Scripts/MenuManager.cs:33)

Here is the code that contains the instantiate command mentioned in the error.

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 public class MultiplayerManager : MonoBehaviour
 {
     public static MultiplayerManager instance;
     public string PlayerName;
     private string MatchName = "";
     private int MaxUsers = 32;
     private string MatchPassword = "";
     public int altprefix;
     public bool MatchStarted = false;
     public bool MatchedLoaded = false;
     
     public List<MpPlayer> PlayerList = new List<MpPlayer>();
     public List<RoomSettings> RoomSettings = new List<RoomSettings>();
     
     public RoomSettings Settings = null;
     
     public MpPlayer MyPlayer;
     public GameObject[] SpawnPoints;
     
     public GameObject PlayerManagerPrefab;
             
     void Start(){
         Application.targetFrameRate = 60;
         instance = t$$anonymous$$s;
         PlayerName = PlayerPrefs.GetString("PlayerName");
         Settings = RoomSettings[0];
         DontDestroyOnLoad(gameObject);
     }
     
     public void StartServer(string Name, string Password, int MaxPlayers){
         MatchName = Name;
         MatchPassword = Password;
         MaxUsers = MaxPlayers;
         Network.InitializeServer(MaxPlayers,2550,true);
         MasterServer.RegisterHost("TDM",MatchName,"Comment");
         //Network.InitializeSecurity();
     }
     
     void OnServerInitialized(){
         ServerPlayerJoinRequest(PlayerName,Network.player);    
     }
     
     void OnConnectedToServer(){
         networkView.RPC("ServerPlayerJoinRequest",RPCMode.Server,PlayerName,Network.player);
     }
     
     void OnPlayerConnected(NetworkPlayer player) {
         foreach(MpPlayer pl in PlayerList){
             networkView.RPC("ClientAddPlayerToList",player,pl.PlayerName,pl.PlayerNetwork);    
         }
         networkView.RPC("Client_GetMatchSettings",player,Settings.MapLoadName,"","");    
     }
     
     void OnPlayerDisconnected(NetworkPlayer id){
         networkView.RPC("RemovePlayerToList",RPCMode.All,id);    
     }
     
     void OnDisconnectedFromServer(NetworkDisconnection info) {
         PlayerList.Clear();    
     }
     
     [RPC]
     void ServerPlayerJoinRequest(string PlayerName, NetworkPlayer View){
         networkView.RPC("ClientAddPlayerToList",RPCMode.All,PlayerName,View);
     }
     
     [RPC]
     void ClientAddPlayerToList(string PlayerName, NetworkPlayer View){
         
         
         if(Network.player == View){
             MpPlayer tempPlayer = new MpPlayer();
             MyPlayer = tempPlayer;
             
             tempPlayer.PlayerName = PlayerName;
             tempPlayer.PlayerNetwork = View;
             
             //GameObject Player = 
             GameObject Player = Network.Instantiate(PlayerManagerPrefab,Vector3.zero,Quaternion.identity,0) as GameObject;
             
             Player.GetComponent<PlayerManager>().t$$anonymous$$sPlayer = MyPlayer;
             
             PlayerList.Add(tempPlayer);
         }
     }
     
     [RPC]
     void RemovePlayerToList(NetworkPlayer View){
         MpPlayer temp = new MpPlayer();
         foreach(MpPlayer pl in PlayerList){
             if(pl.PlayerNetwork == View){
                 temp = pl;    
             }
                 
         }
         if(temp != null){
             PlayerList.Remove(temp);
             Network.Destroy(temp.PlayerManager.gameObject);
         }
             
     }
     
     [RPC]
     void Client_GetMatchSettings(string map, string mode,string others){
         Settings = GetMap(map);
     }
     
     public RoomSettings GetMap(string name){
         RoomSettings get = null;
         
         foreach(RoomSettings rs in RoomSettings){
             if(rs.MapLoadName == name){
                 get = rs;
                 break;
             }
         }
         
         return get;
     }
     
     [RPC]
     void Client_LoadMap(string map, int prefix){
         //Network.SetLevelPrefix(prefix);
         Application.LoadLevel(map);
     }
     
     void OnGUI(){
         if(!MyPlayer.PlayerIsAlive && MatchedLoaded)
             SpawnMenu();
         if(MyPlayer.PlayerIsAlive){
             if(GUILayout.Button("Suicide"))
                 MyPlayer.PlayerManager.HandleBulletDamage(100);
         }
         
     }
     
     [RPC]
     void Server_SpawnPlayer(NetworkPlayer Player){
         int numberSpawn = Random.Range(0,SpawnPoints.Length);
         networkView.RPC("Client_SpawnPlayer",RPCMode.All,Player,SpawnPoints[numberSpawn].transform.position,SpawnPoints[numberSpawn].transform.rotation);    
     }
     [RPC]
     void Client_SpawnPlayer(NetworkPlayer Player, Vector3 Pos, Quaternion Rot){
         MultiplayerManager.GetMPPlayer(Player).PlayerIsAlive = true;
         if(Player == MyPlayer.PlayerNetwork){
             MyPlayer.PlayerManager.ControllerTranform.position = Pos;
             MyPlayer.PlayerManager.ControllerTranform.rotation = Rot;
             MyPlayer.PlayerManager.networkView.RPC("Client_ImAlive",RPCMode.All);
     //    }else{
                 
         }
     }
     
     void OnLevelWasLoaded(){
         MatchedLoaded = true;
         if(Application.loadedLevelName == Settings.MapName && Network.isServer){
             SpawnPoints = GameObject.FindGameObjectsWithTag("SpawnPoint");    
             networkView.RPC("Client_ServerLoaded",RPCMode.AllBuffered);
         }
     }    
     
     [RPC]
     void Client_ServerLoaded(){
         MatchStarted = true;    
     }
     
     public static MpPlayer GetMPPlayer(NetworkPlayer Player){
         foreach(MpPlayer pl in MultiplayerManager.instance.PlayerList){
             if(pl.PlayerNetwork == Player)
                 return pl;
         }
         return null;
     }
     
     void SpawnMenu(){
         
             if(GUI.Button(new Rect(5,Screen.height-40,250,35),"Spawn"))
             {
                 if(Network.isServer)
                     Server_SpawnPlayer(Network.player);
                 else
                     networkView.RPC("Server_SpawnPlayer",RPCMode.Server,Network.player);    
             }
         }
     
 }
 [System.Serializable]
 public class MpPlayer {
     public string PlayerName = "";
     public NetworkPlayer PlayerNetwork;
     public PlayerManager PlayerManager;
     public int PlayerHealth = 100;
     public bool PlayerIsAlive;
     public int PlayerKills;
     public int PlayerDeaths;
 }
 [System.Serializable]
 public class RoomSettings{
     public string MapName;
     public string MapLoadName;
     
 }