From 82981391c83616b1062262d12d59b449de0d16fb Mon Sep 17 00:00:00 2001
From: sta <sta.blockhead@gmail.com>
Date: Fri, 11 Aug 2017 17:13:25 +0900
Subject: [PATCH] [Modify] Throw exception

---
 websocket-sharp/Server/WebSocketSessionManager.cs | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/websocket-sharp/Server/WebSocketSessionManager.cs b/websocket-sharp/Server/WebSocketSessionManager.cs
index 2c8e668b..b541a029 100644
--- a/websocket-sharp/Server/WebSocketSessionManager.cs
+++ b/websocket-sharp/Server/WebSocketSessionManager.cs
@@ -932,7 +932,12 @@ namespace WebSocketSharp.Server
     public bool PingTo (string message, string id)
     {
       IWebSocketSession session;
-      return TryGetSession (id, out session) && session.Context.WebSocket.Ping (message);
+      if (!TryGetSession (id, out session)) {
+        var msg = "The session could not be found.";
+        throw new ArgumentException (msg, "id");
+      }
+
+      return session.Context.WebSocket.Ping (message);
     }
 
     /// <summary>