* result is set to \p NULL. Possible errors include: \p E_BAD_TABLE, \p
* E_BAD_STORAGE_FLAGS, errors returned by get_mapped_object(), \p
* E_RB_KEY_NOT_FOUND.
* result is set to \p NULL. Possible errors include: \p E_BAD_TABLE, \p
* E_BAD_STORAGE_FLAGS, errors returned by get_mapped_object(), \p
* E_RB_KEY_NOT_FOUND.