I have added a method to fail and display a simple message to the user instead of an error dialog.
http://bazaar.launchpad.net/~kovid/c...revision/12162
If you want to use it in your recipe and have your recipe remain compatible with older calibre versions, do this
Code:
if hasattr(self, 'abort_recipe_processing'):
self.abort_recipe_processing('Pocket download aborted as no new articles found')