Check that .ui-dialog-content exists before attempting to manipulate it

js/builder.js

@@ -267,6 +267,9 @@
         window.innerHeight || document.documentElement.clientHeight;
       if (bounding.bottom > viewPortHeight) {
         const $dialog = $('.ui-dialog-content', dialog);
+        if ($dialog.length === 0) {
+          return;
+        }
         const height = viewPortHeight - 200;
         $dialog.dialog('option', 'height', height);
         $dialog[0].style.overscrollBehavior = 'contain';