Neplatný výraz PathExpression. Musí to být StateFieldPathExpression

Myslím, že problém je v WHERE NOT .zkuste tento dotaz:

$query = $em->createQuery(
                            'SELECT r ' .
                            'FROM AppBundle:Room r ' .
                            'WHERE r NOT IN ( ' .
                            'SELECT b.room ' .
                            'FROM AppBundle:Bookings b ' .
                            'WHERE  ' .
                            'b.check_out < :check_in ' .
                            'OR ' .
                            'b.check_in > :check_out ' .
                            ') ' .
                            'ORDER BY r.id'
                    )
                    ->setParameter('check_in', $request->query->get('check-in'))
                    ->setParameter('check_out', $request->query->get('check-out'));