From 4b2e166481e47326d082d5f3a49f0eb0eacc5e72 Mon Sep 17 00:00:00 2001
From: sta <sta.blockhead@gmail.com>
Date: Tue, 25 Sep 2018 19:45:08 +0900
Subject: [PATCH] [Modify] Throw exception

---
 websocket-sharp/Net/HttpUtility.cs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/websocket-sharp/Net/HttpUtility.cs b/websocket-sharp/Net/HttpUtility.cs
index 7a5de1c7..97d73dc2 100644
--- a/websocket-sharp/Net/HttpUtility.cs
+++ b/websocket-sharp/Net/HttpUtility.cs
@@ -819,7 +819,10 @@ namespace WebSocketSharp.Net
 
     public static string HtmlAttributeEncode (string s)
     {
-      if (s == null || s.Length == 0)
+      if (s == null)
+        throw new ArgumentNullException ("s");
+
+      if (s.Length == 0)
         return s;
 
       var buff = new StringBuilder ();