Warning when deleting an item that is used as default

As a systems administrator, I want alloy to warn me (with a list of designs) if I am about to delete an item that is an attribute's default value on a design, so that users can continue to create items.

Example:

(Job)Dropped Kerb Request

(Lookup)Kerb Type: A, B, C

Default Kerb Type = C

Default Kerb Type Item C is subsequently deleted. On creation of Dropped Kerb Request Alloy cannot load default item, and user cannot proceed with job creation.