Expired links (#94)

1. Handle expired links on signup
2.Reject invitations when user is already a member
3. Make sure not to display errors due to Next.js redirection during team creation
4. Fix documentation sidebar

apps/web/app/(marketing)/docs/_components/docs-navigation.tsx

@@ -92,6 +92,10 @@ function Tree({
     ));
   }
 
+  if (pages.length === 0) {
+    return null;
+  }
+
   return (
     <SidebarMenuSub>
       {pages.map((treeNode, index) => (