From e64daf6d81fa580984960709d889cfa1c685d76a Mon Sep 17 00:00:00 2001
From: sta <sta.blockhead@gmail.com>
Date: Tue, 15 Aug 2017 16:41:50 +0900
Subject: [PATCH] [Modify] Throw exception

---
 websocket-sharp/Server/WebSocketSessionManager.cs | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/websocket-sharp/Server/WebSocketSessionManager.cs b/websocket-sharp/Server/WebSocketSessionManager.cs
index ca40c9ab..41577490 100644
--- a/websocket-sharp/Server/WebSocketSessionManager.cs
+++ b/websocket-sharp/Server/WebSocketSessionManager.cs
@@ -1148,8 +1148,12 @@ namespace WebSocketSharp.Server
     public void SendToAsync (string data, string id, Action<bool> completed)
     {
       IWebSocketSession session;
-      if (TryGetSession (id, out session))
-        session.Context.WebSocket.SendAsync (data, completed);
+      if (!TryGetSession (id, out session)) {
+        var msg = "The session could not be found.";
+        throw new ArgumentException (msg, "id");
+      }
+
+      session.Context.WebSocket.SendAsync (data, completed);
     }
 
     /// <summary>