Fixed bug that errors in http communication are not propagated correctly if response is empty.

Author: oliverhanappi

RestSharp/Extensions/MiscExtensions.cs

@@ -106,7 +106,9 @@ public static string AsString(this JToken token, CultureInfo culture)
 		/// <param name="buffer">An array of bytes to convert</param>
 		/// <returns>The byte as a string.</returns>
 		public static string AsString(this byte[] buffer)
-		{
+		{
+            if (buffer == null) return "";
+
 			// Ansi as default
 			Encoding encoding = Encoding.UTF8;