ezfeZPSolrQueryBuilder::policyLimitationFilterQuery():
If $limitation is not an array AND $limitationType is 'Group' or 'Owner', $currentUser will be used uninitialized and this will crash. (In master, only 'Owner' is affected.)

Either $currentUser should be initialized at the beginning of the method, or eZUser::currentUser() should be used directly as it is in 'Group' on master.