fix(content-docs): render category with no subitems as a normal link (#6495)

packages/docusaurus-plugin-content-docs/src/sidebars/processor.ts

@@ -117,6 +117,34 @@ async function processSidebar(
     item: NormalizedSidebarItem,
   ): Promise<SidebarItem[]> {
     if (item.type === 'category') {
+      // If the current category doesn't have subitems, we render a normal doc link instead.
+      if (item.items.length === 0) {
+        if (!item.link) {
+          throw new Error(
+            `Sidebar category ${item.label} has neither any subitem nor a link. This makes this item not able to link to anything.`,
+          );
+        }
+        switch (item.link.type) {
+          case 'doc':
+            return [
+              {
+                type: 'doc',
+                label: item.label,
+                id: item.link.id,
+              },
+            ];
+          case 'generated-index':
+            return [
+              {
+                type: 'link',
+                label: item.label,
+                href: item.link.permalink,
+              },
+            ];
+          default:
+            throw new Error('Unexpected sidebar category link type');
+        }
+      }
       return [await processCategoryItem(item)];
     }
     if (item.type === 'autogenerated') {