feat: support authentik aouth2.

api/errors.go

@@ -32,6 +32,7 @@ var errorForbiddenEdit = errors.New("You cannot edit someone else's comment.")
 var errorMissingSmtpAddress = errors.New("Missing SMTP_FROM_ADDRESS")
 var errorSmtpNotConfigured = errors.New("SMTP is not configured.")
 var errorOauthMisconfigured = errors.New("OAuth is misconfigured.")
+var errorOauthDiscoveryFailed = errors.New("OAuth discovery is failed.")
 var errorCannotReadResponse = errors.New("Cannot read response.")
 var errorNotModerator = errors.New("You need to be a moderator to do that.")
 var errorNotADirectory = errors.New("The given path is not a directory.")