fix: preserve article sidebar when TOC is empty

assets/js/page-template.js

@@ -111,10 +111,11 @@
 
     if (!hasToc) {
       tocWidgets.forEach(function (box) {
-        var host = box.closest('.widget') || box.parentElement;
+        var widget = box.closest('.widget');
-        // Prefer removing the whole widget chrome when empty.
+        // A built-in TOC is a direct child of the article sidebar.  Its parent
-        if (host && host !== document.body && host.querySelectorAll('.posts-nav-box').length <= 1) {
+        // is therefore not widget chrome and must never be removed here.
-          host.remove();
+        if (widget && widget !== document.body && widget.querySelectorAll('.posts-nav-box').length <= 1) {
+          widget.remove();
         } else {
           box.remove();
         }