From 74cd02dace59cf16183db2b8e062ee61a32cf734 Mon Sep 17 00:00:00 2001
From: sta <sta.blockhead@gmail.com>
Date: Wed, 23 May 2018 19:02:37 +0900
Subject: [PATCH] [Modify] Throw exception

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

diff --git a/websocket-sharp/Server/WebSocketBehavior.cs b/websocket-sharp/Server/WebSocketBehavior.cs
index 68c3a1b7..66f1c36e 100644
--- a/websocket-sharp/Server/WebSocketBehavior.cs
+++ b/websocket-sharp/Server/WebSocketBehavior.cs
@@ -596,8 +596,12 @@ namespace WebSocketSharp.Server
     /// </param>
     protected void SendAsync (FileInfo file, Action<bool> completed)
     {
-      if (_websocket != null)
-        _websocket.SendAsync (file, completed);
+      if (_websocket == null) {
+        var msg = "The current state of the connection is not Open.";
+        throw new InvalidOperationException (msg);
+      }
+
+      _websocket.SendAsync (file, completed);
     }
 
     /// <summary>