Unity stop when compiling, with a script using Photon Chat

Hi, I have a problem with Unity : it stop without any error message or Debug Error. This occurs while Unity compiles after doing a build of the project or compiling a script. The compilation logo runs, then everything stops, Unity doesn't response anymore but Windows doesn't show any problem like : "Unity does not answer ..." . I have to close it with the task manager because the Unity window does not respond at all. Even in a quarter of an hour, Unity is not restarted or closed ... Moreover, the problem is there since the creation of a particular script. Do you have any answers for this problem ?

The script :

 public class Chat : MonoBehaviour, IChatClientListener
 {
     public void DebugReturn(DebugLevel level, string message)
     {
         if (level == ExitGames.Client.Photon.DebugLevel.ERROR)
         {
             Debug.LogError(message);
         }
         else if (level == ExitGames.Client.Photon.DebugLevel.WARNING)
         {
             Debug.LogWarning(message);
         }
         else
         {
             Debug.Log(message);
         }
     }
 
     public void OnChatStateChange(ChatState state)
     {
     }
 
     public void OnConnected()
     {
         Debug.Log("Connected");
         chatClient.Subscribe(new string[] { "test" }, 0);
     }
 
     public void OnDisconnected()
     {
         Debug.Log("Disconnected");
     }
 
     public void OnGetMessages(string channelName, string[] senders, object[] messages)
     {
         Debug.Log("Received message from channel : " + channelName + " that say : " + messages[0]);
     }
 
     public void OnPrivateMessage(string sender, object message, string channelName)
     {
     }
 
     public void OnStatusUpdate(string user, int status, bool gotMessage, object message)
     {
     }
 
     public void OnSubscribed(string[] channels, bool[] results)
     {
         Debug.Log("Subscribed");
     }
 
     public void OnUnsubscribed(string[] channels)
     {
     }
 
     public void OnUserSubscribed(string channel, string user)
     {
         Debug.Log("User Subscribed");
     }
 
     public void OnUserUnsubscribed(string channel, string user)
     {
     }
 
     ChatClient chatClient;
     AppSettings chatAppSettings;
 
     private void Start()
     {
         chatClient = new ChatClient(this);
         chatClient.ChatRegion = "EU";
         chatAppSettings = PhotonNetwork.PhotonServerSettings.AppSettings;
         this.chatClient.UseBackgroundWorkerForSending = true;
         chatClient.Connect(chatAppSettings.AppIdChat, "1.0", new Photon.Chat.AuthenticationValues("Player"));
     }
 
     private void Update()
     {
         if (Input.GetKeyDown(KeyCode.P))
         {
             chatClient.PublishMessage("test", "This is a test");
         }
         chatClient.Service();
     }
 }