I have tried to follow your advice, by changing mappedBy="tab") to mappedBy="id"), as dragon_sa have suggested and the whole tab-file, as suggested by Crezzur, but it did change anything to my error.
I still have this error:
PrestaShopBundle\Entity\Tab
The association PrestaShopBundle\Entity\Tab#tabLangs refers to the owning side field PrestaShopBundle\Entity\TabLang#tab which does not exist.
I use Prestashop 1.7.7.5