fixes #2692: Rework bookmarklet preview

app/assets/javascripts/notes.js

@@ -176,6 +176,9 @@ Danbooru.Note = {
 
     scale_all: function() {
       var container = document.getElementById('note-container');
+      if (container === null) {
+        return;
+      }
       // Hide notes while rescaling, to prevent unnecessary reflowing
       var was_visible = container.style.display != 'none';
       if (was_visible) {