Trigger the recalculating event on null when the binding does not exist

srcjs/shinyapp.js

@@ -510,7 +510,7 @@ var ShinyApp = function() {
   addCustomMessageHandler('recalculating', function(message) {
     if (message.hasOwnProperty('name') && message.hasOwnProperty('status')) {
       var binding = this.$bindings[name];
-      $(binding ? binding.el : document).trigger({
+      $(binding ? binding.el : null).trigger({
         type: 'shiny:' + message.status
       });
     }