Why doesn't Grails notify me of error at domain object saving?

I'm just starting with Grails, and here is the first issue.

I spent several hours to find out that domain object cannot be inserted in DB, until all its properties are populated.

class Item {
  String title
  String link
}

class ItemController {
  def fetch = {
    def item = new Item()
    item.title = "blabla"
    // no value for "link"
    item.save()
  }
}

Looks logical, but why is it skipped so silently? Can I configure something to get exceptions in such cases?

Thanks