$c = Doctrine::getTable('Contact')->findOneById($id);
$c->get('Categories', false);
$c->save();

PHP Fatal error:  Call to a member function save() on a non-object in /lib/vendor/symfony/lib/plugins/sfDoctrinePlugin/lib/vendor/doctrine/Doctrine/Connection/UnitOfWork.php on line 443
PHP Stack trace:
PHP   1. {main}() /test/doctrine/get_with_no_load_corrupt_many_to_many_assoc_.php:0
PHP   2. Doctrine_Record->save() /test/doctrine/get_with_no_load_corrupt_many_to_many_assoc_.php:51
PHP   3. Doctrine_Connection_UnitOfWork->saveGraph() /lib/vendor/symfony/lib/plugins/sfDoctrinePlugin/lib/vendor/doctrine/Doctrine/Record.php:1705
PHP   4. Doctrine_Connection_UnitOfWork->saveAssociations() /lib/vendor/symfony/lib/plugins/sfDoctrinePlugin/lib/vendor/doctrine/Doctrine/Connection/UnitOfWork.php:137