Set up callback handler on start and not dynamically

Since we can't do it dynamically

esi_sso.go

@@ -83,6 +83,7 @@ func NewSSO(clientID, redirectURI string, scopes []string) (*SSO, error) {
 func (s *SSO) SetRouter(r *router.Router) {
 	s.router = r
 	logger.Debug("SSO configured to use existing fasthttp router")
+	s.setupCallbackHandler()
 }
 
 func (s *SSO) initDB() error {
@@ -186,7 +187,6 @@ func (s *SSO) startAuthFlow(ctx context.Context, characterName string) error {
 		return errors.New("no router configured for callback handling")
 	}
 	logger.Debug("Using fasthttp router for callback handling")
-	s.setupCallbackHandler()
 
 	// Wait for callback
 	logger.Debug("Waiting for authentication callback")