Can't add/edit products

[mendedwraith]

When logged in as superadmin, I go to ../admin/product/new and I get an error Could not load type Application\Vespolina\ProductBundle\Form\Type\ProductFormExtendedType

I tried adding the necessary config.

And I got this error

The form's view data is expected to be an instance of class Application\Vespolina\ProductBundle\Document\Product, but is a(n) string. You can avoid this error by setting the "data_class" option to null or by adding a view transformer that transforms a(n) string to an instance of Application\Vespolina\ProductBundle\Document\Product.