Logout not shown in examples and clicking the sign out link throws error

[Kumar-Ashwin-Hubert]

The logout functionality is not shown in any samples as compared to that of AuthBot.
On seeing the code, this function does the logout

public async Task Logout(AuthenticationOptions authOptions, IDialogContext context)
        {
            context.UserData.RemoveValue($"{this.Name}{ContextConstants.AuthResultKey}");
            context.UserData.RemoveValue($"{this.Name}{ContextConstants.MagicNumberKey}");
            context.UserData.RemoveValue($"{this.Name}{ContextConstants.MagicNumberValidated}");
            string signoutURl = "https://login.microsoftonline.com/common/oauth2/logout?post_logout_redirect_uri=" + System.Net.WebUtility.UrlEncode(authOptions.RedirectUrl);
            await context.PostAsync($"In order to finish the sign out, please click at this [link]({signoutURl}).");
        }

But on calling it, and clicking the link replied back, I get the following error message in browser:

[Kumar-Ashwin-Hubert]

#34