fix: add 404 response to OpenAPI spec, fix TypeScript type for optional title

autogpt_platform/backend/backend/api/features/chat/routes.py

@@ -216,6 +216,7 @@ async def create_session(
     "/sessions/{session_id}",
     dependencies=[Security(auth.requires_user)],
     status_code=204,
+    responses={404: {"description": "Session not found or access denied"}},
 )
 async def delete_session(
     session_id: str,

autogpt_platform/frontend/src/app/(platform)/copilot/components/ChatSidebar/ChatSidebar.tsx

@@ -31,7 +31,7 @@ export function ChatSidebar() {
   const [sessionId, setSessionId] = useQueryState("sessionId", parseAsString);
   const [sessionToDelete, setSessionToDelete] = useState<{
     id: string;
-    title: string | null;
+    title: string | null | undefined;
   } | null>(null);
 
   const queryClient = useQueryClient();
@@ -79,7 +79,7 @@ export function ChatSidebar() {
   function handleDeleteClick(
     e: React.MouseEvent,
     id: string,
-    title: string | null,
+    title: string | null | undefined,
   ) {
     e.stopPropagation(); // Prevent session selection
     if (isDeleting) return; // Prevent double-click during deletion