Form responses must redirect to another location

gistfile1.txt

    public function search(int $page =1, Request $request, SessionInterface $session, SearchService $searchService)
    {

        $searchType = null;
        $result     = null;
        $queryList  = [];
        $tmp        = [];
        
        $result = $searchService->handleSearchRequest($request, $page);

        $selection = $session->get('selection');

        if($result)
        {

            if($searchService->getDisplay() == "grid")
            {
                $template = 'search/result_grid.html.twig';                   
            }
            else
            {
                $template = 'search/result.html.twig';
            }

            return $this->renderForm($template, [
                'result'    => $result,
                'total'     => $result[0]['full_count'],
                'page'      => $page,
                'selection' => $selection,
                'searchService' => $searchService->toArray()
            ]);
        }

        return $this->redirectToRoute('index');

    }