PHP错误 - 带子类别的Opencart 3.0.3.2图像

Question

(I know there are questions on this for previous versions of Opencart but I am using 3.0.3.2. I am getting a php error when I alter the code to incorporate images in the Refine Search. (The linked computer images are just placeholders.)

I tried altering code in catalog/controller/product/category.php

 if ($category_info['image']) {
            $data['thumb'] = $this->model_tool_image->resize($category_info['image'], $this->config->get('theme_' . $this->config->get('config_theme') . '_image_category_width'), $this->config->get('theme_' . $this->config->get('config_theme') . '_image_category_height'));
        } else {
            $data['thumb'] = '';
        }

        $data['description'] = html_entity_decode($category_info['description'], ENT_QUOTES, 'UTF-8');
        $data['compare'] = $this->url->link('product/compare');

        $url = '';

        if (isset($this->request->get['filter'])) {
            $url .= '&filter=' . $this->request->get['filter'];
        }

        if (isset($this->request->get['sort'])) {
            $url .= '&sort=' . $this->request->get['sort'];
        }

        if (isset($this->request->get['order'])) {
            $url .= '&order=' . $this->request->get['order'];
        }

        if (isset($this->request->get['limit'])) {
            $url .= '&limit=' . $this->request->get['limit'];
        }


        $product_total = $this->model_catalog_product->getTotalProducts($filter_data);

        $results = $this->model_catalog_product->getProducts($filter_data);

I get an undefined variable error on lines 135 and 137 (last lines of code above).