Unclear exception thrown when a user doesn't have access to the collection but the collectionfilter is displayed

[JeffersonBledsoe]

If a user does not have the correct permissions to view the collection but the filter is displayed, the collectionish variable in the following code is None and so throws an exception:

collective.collectionfilter/src/collective/collectionfilter/baseviews.py

Lines 110 to 113 in 507c386

	collectionish = (
	ICollectionish(self.collection.getObject()) if self.collection else None
	)
	selector = collectionish.content_selector

AccessControl.Unauthorized is likely to be a more suitable exception.