Update the demo program to show the use of the new exception types

Author: angusmillar

SmartHealthCard.DecoderDemo/Program.cs

@@ -57,17 +57,28 @@ static async Task DecoderDemoRunner()
       }
       catch (SmartHealthCardSignatureInvalidException SignatureInvalidException)
       {
-        Console.WriteLine("The SMART Health Card is invalid");
+        //The decoder successfully validated the JWS signature and found it to be invalid
+        Console.WriteLine("The SMART Health Card's signing signature is invalid");
         Console.WriteLine(SignatureInvalidException.Message);
       }
+      catch (SmartHealthCardJwksRequestException JwksRequestException)
+      {
+        //The decoder was unable to retrieved JWKS file that contains the token's public signing key.
+        //This is likely due to an Internet connectivity issue, the exception message will say more.
+        Console.WriteLine("The SMART Health Card's public key can not be retrieved.");
+        Console.WriteLine(JwksRequestException.Message);
+      }
       catch (SmartHealthCardDecoderException DecoderException)
       {
-        Console.WriteLine("The SMART Health Card Decoder has found an error, please see message below::");
+        //The decoder ran into an error while attempting to decode the JWS token and its SMART Health card payload.
+        //It is likely that the SMART Health card token is incorrectly structured 
+        Console.WriteLine("The SMART Health Card Decoder has encountered an error, please see message below::");
         Console.WriteLine(DecoderException.Message);
       }
       catch (Exception Exception)
       {
-        Console.WriteLine("Oops, there is an unexpected development exception");
+        //Any unexpected errors that the decoder did not protect against. 
+        Console.WriteLine("Oops, there is an unexpected development exception.");
         Console.WriteLine(Exception.Message);
       }
     }