I just upgraded from 1.6.1.5 to 1.7.8.4 and I get an error when I do install/upgrade/upgrade.php

[OGLIOTTI Benjamin]

Fatal error: Uncaught Symfony\Component\Debug\Exception\ContextErrorException: Notice: Undefined offset: 0 in /home/sc4nxjf6534/nailartboutique-v1.6.7.sc4nxjf6534.universe.wf/install/upgrade/php/p16012_pack_rework.php:84 Stack trace: #0 /home/sc4nxjf6534/nailartboutique-v1.6.7.sc4nxjf6534.universe.wf/install/upgrade/php/p16012_pack_rework.php(41): getItems('8760') #1 [internal function]: p16012_pack_rework() #2 /home/sc4nxjf6534/nailartboutique-v1.6.7.sc4nxjf6534.universe.wf/src/PrestaShopBundle/Install/Upgrade.php(477): call_user_func_array('p16012_pack_rew...', Array) #3 /home/sc4nxjf6534/nailartboutique-v1.6.7.sc4nxjf6534.universe.wf/src/PrestaShopBundle/Install/Upgrade.php(826): PrestaShopBundle\Install\Upgrade->upgradeDb(Array) #4 /home/sc4nxjf6534/nailartboutique-v1.6.7.sc4nxjf6534.universe.wf/install/upgrade/upgrade.php(93): PrestaShopBundle\Install\Upgrade->run() #5 {main} thrown in /home/sc4nxjf6534/nailartboutique-v1.6.7.sc4nxjf6534.universe.wf/install/upgrade/php/p16012_pack_rework.php on line 84