Hello,
I tried with your example and it displays the same exception for me.
By looking into the documentation, it looks like this should out of the box, but it doesn't.
They highlight the PrestaShopBundle\Controller\Admin\Improve\Design\CmsPageController in there, which works as expected if you try to decorate it. The main difference between these classes seems to be the fact that the Product one has a constructor.
This is one way you can achieve what you want:
1. In your services.yml, define the product service as well as follows:
PrestaShopBundle\Controller\Admin\Sell\Catalog\Product\ProductController:
autowire: true
2. Now you should be able to decorate the PrestaShopBundle\Controller\Admin\Sell\Catalog\Product\ProductController service. In your decorator please add autowire: true as well, in order to avoid another exception.
3. As stated in the documentation, you will need to run bin/console cache:clear in order for your decorator to override the routes exposed by the default controller.
Let me know if the above helps.