Can't save resource if alias already exist

[Spheerys]

There is a annoying behavior when you are in this configuration :

• a Collection of resources
• an activated Custom Forms for theses resources with the field alias hidden

If you already have a resource with a specific alias, if you create (several weeks!) after another resource with the same alias, you don't get any error and your new resource is not registered.

of course, if I show the alias field on my custom form, I show the error. But maybe it's a MODX issue and not a Collection one. Just I was "traped" two times on this situation and I wonder if there is no possibility to improved the registration process under Collection in case of duplicate