Update NetPeer.cs

Fixed an issue in the `WaitMessage(int)` when `MessageReceivedEvent` is signaled, yet `ReadMessage()` returns null.

Lidgren.Network/NetPeer.cs

@@ -182,12 +182,21 @@ namespace Lidgren.Network
 		/// </summary>
 	        public NetIncomingMessage WaitMessage(int maxMillis)
 	        {
-			var msg = ReadMessage();
+	            NetIncomingMessage msg = ReadMessage();
-			if (msg != null)
+	
-				return msg; // no need to wait; we already have a message to deliver
+	            while (msg == null)
-			var msgEvt = MessageReceivedEvent;
+	            {
-			msgEvt.WaitOne(maxMillis);
+	                // This could return true...
-			return ReadMessage();
+	                if (!MessageReceivedEvent.WaitOne(maxMillis))
+	                {
+	                    return null;
+	                }
+	
+	                // ... while this will still returns null. That's why we need to cycle.
+	                msg = ReadMessage();
+	            }
+	
+	            return msg;
         	}
 
 		/// <summary>