Problem with cron when node import module is enabled

When running cron with node import enabled, the following problem happens:

notice: Undefined property: stdClass::$profile_dob in birthdays_load_user() (line 658 of {PATH}/sites/all/modules/birthdays/birthdays.module).

This can easily be fixed by checking if the property is set prior to doing things with it. I've attached a patch which should fix this.