[BUGFIX] Enable links for SingleProduct plugin

Link from the cart product list to products
which are put into the cart from a
landing page (doktype `183`) via the plugin
`cartproducts_singleproduct` are no correctly
resolved.

Author: rintisch

Classes/Controller/ProductController.php

@@ -185,7 +185,7 @@ public function showAction(Product $product = null): ResponseInterface
     {
         if ((int)$GLOBALS['TSFE']->page['doktype'] === 183) {
             $productUid = (int)$GLOBALS['TSFE']->page['cart_products_product'];
-            $product =  $this->productRepository->findByUid($productUid);
+            $product = $this->productRepository->findByUid($productUid);
         }
 
         $this->view->assign('product', $product);
@@ -349,18 +349,24 @@ protected function restoreSession(): void
     private function getDetailLinkData(Request $request): array
     {
         $frontendController = $request->getAttribute('frontend.controller');
+        $detailPageUid = $frontendController->getRequestedId();
+
         $requestArguments = $frontendController->getPageArguments()->getArguments();
 
         $pluginNamespace = preg_grep('/tx_cartproducts_.*/', array_keys($requestArguments));
         $pluginNamespace = array_shift($pluginNamespace);
 
+        if (!$pluginNamespace) {
+            return [
+                'uid' => $detailPageUid,
+            ];
+        }
+
         $pluginArguments = $requestArguments[$pluginNamespace];
         $controller = $pluginArguments['controller'];
         $action = $pluginArguments['action'];
         $pluginName = preg_replace('/tx_cartproducts_/', '', $pluginNamespace);
 
-        $detailPageUid = $frontendController->getRequestedId();
-
         return [
             'uid' => $detailPageUid,
             'pluginName' => $pluginName,