Codeigniter 4 Pagination 404 File Not Found error - codeigniter

Question

I'm really struggling to overcome a 404 File Not Found error in CI4 since adding pagination to the Model function. I'm assuming it's to do with routing alone as it's also throwing up the same error on my subbrand_name page, which doesn't include any pagination in its Model code and was working fine until I added pagination to the brand_name page.
My Routes file:
$routes->get('shop/brands/(:segment)', 'Shop::brand_name/$1');
$routes->get('shop/brands/(:segment)/(:segment)', 'Shop::subbrand_name/$1/$2');
My Controller:
public function brand_name($brand_name_slug)
{
$model = new ShopModel();
$data = [
'category_menu' => $model->category_menu(),
'brand_menu' => $model->brand_menu(),
'nav' => $model->nav(),
'subnav' => $model->subnav(),
'shop' => $model->brand_name($brand_name_slug),
'pager' => $model->pager
];
if (empty($data['shop']))
{
throw new \CodeIgniter\Exceptions\PageNotFoundException('Cannot find the news item: '. $slug);
}
echo view('templates/header', $data);
echo view('shop/view', $data);
echo view('templates/footer', $data);
}
My Model:
public function brand_name($brand_name_slug)
{
return $this
->table('shop a')
->select()
->join('(SELECT sku, MIN(sale_price) AS sale_price FROM shop GROUP BY sku) AS b', 'a.sku = b.sku AND a.sale_price = b.sale_price')
->where('availability', 'in stock')
->where('a.sku !=', '')
->where('brand_name_slug', $brand_name_slug)
->groupBy('a.sku')
->orderBy('brand_name, subbrand_name, product, size, unit')
->paginate(15);
}

Answer 1

Turns out, it was nothing to do with routing... just simply, my JOIN was buggy.
Managed to sort it by replacing shop a and a.sku in the JOIN part of the argument with shop and shop.sku. Worked perfectly... FINALLY!
public function brand_name($brand_name_slug)
{
return $this
->table('shop')
->select('*')
->join('(SELECT sku, MIN(sale_price) AS sale_price FROM shop GROUP BY sku) AS b', 'shop.sku = b.sku AND shop.sale_price = b.sale_price')
->where('availability', 'in stock')
->where('shop.sku !=', '')
->where('brand_name_slug', $brand_name_slug)
->groupBy('shop.sku')
->orderBy('brand_name, subbrand_name, product, size, unit')
->paginate(15);
}