From 3a5d05cb21e534552e72e0e748784897257cb0d6 Mon Sep 17 00:00:00 2001
From: NZSmartie <nzsmartie@gmail.com>
Date: Sun, 3 Dec 2017 19:57:10 +1300
Subject: [PATCH] Return a placeholder option to give the application chance at
 reading them

---
 src/CoAPNet/Options/OptionFactory.cs | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/CoAPNet/Options/OptionFactory.cs b/src/CoAPNet/Options/OptionFactory.cs
index 709dbc5..43c5150 100644
--- a/src/CoAPNet/Options/OptionFactory.cs
+++ b/src/CoAPNet/Options/OptionFactory.cs
@@ -85,16 +85,22 @@ public void Register(params Type[] addtionalOptions)
         /// <exception cref="CoapOptionException">If the option number is unsuppported and is critical (See RFC 7252 Section 5.4.1)</exception>
         public CoapOption Create(int number, byte[] data = null)
         {
+            CoapOption option;
             // Let the exception get thrown if index is out of range
-            Type type = null;
-            if (!_options.TryGetValue(number, out type))
+            if (_options.TryGetValue(number, out var type))
             {
+                option = (CoapOption)Activator.CreateInstance(type);
+            }
+            else
+            {
+                // Critial option must be registered as they're esssential for understanding the message
                 if (number % 2 == 1)
                     throw new CoapOptionException($"Unsupported critical option ({number})", new ArgumentOutOfRangeException(nameof(number)));
-                return null;
+
+                // Return a placeholder option to give the application chance at reading them
+                option = new CoapOption(number, type: OptionType.Opaque);
             }
 
-            var option = (CoapOption)Activator.CreateInstance(type);
             if (data != null)
                 option.FromBytes(data);