Don't complain about brains in reference_catalog where getObject retu…

…rns None.

This happens for content without apparent problems.

CHANGES.rst

@@ -5,7 +5,8 @@ Changelog
 1.7 (unreleased)
 ----------------
 
-- Nothing changed yet.
+- Don't complain about brains in ``reference_catalog`` where ``getObject`` returns None.
+  This happens for content without apparent problems.  [maurits]
 
 
 1.6 (2016-08-23)

collective/catalogcleanup/browser.py

@@ -162,6 +162,10 @@ def check_references(self, catalog_id='reference_catalog'):
                 # cleaned up by one of the other methods already.
                 ref_errors += 1
                 continue
+            if ref is None:
+                # No error, but no object either.  This can happen
+                # for references.  Let's accept it.
+                continue
             for getter in getters:
                 obj = self.get_object_or_status(ref, getter)
                 if not isinstance(obj, basestring):