fix:reuse parent ctx cause unexpected stop of App (#1429)

* fix reuse parent ctx cause unexpected stop of App

app.go

@@ -99,10 +99,9 @@ func (a *App) Run() error {
 	}
 	wg.Wait()
 	if a.opts.registrar != nil {
-		var cancel context.CancelFunc
-		ctx, cancel = context.WithTimeout(a.opts.ctx, a.opts.registrarTimeout)
-		defer cancel()
-		if err := a.opts.registrar.Register(ctx, instance); err != nil {
+		rctx, rcancel := context.WithTimeout(a.opts.ctx, a.opts.registrarTimeout)
+		defer rcancel()
+		if err := a.opts.registrar.Register(rctx, instance); err != nil {
 			return err
 		}
 		a.instance = instance