If category image don't exist, this will throw a null on php logs

[rodriciru]

https://github.com/PrestaShop/hummingbird/blob/e1429f34253756117e4f669d48e569748fec9cd1/templates/catalog/_partials/category-header.tpl#L12

I think this only needs {if $category.image} because if {if $category.image} don't exist, the values of large and large.url it will be null or undefined https://github.com/PrestaShop/hummingbird/pull/477