As the error was accomplished through the god Indra, he grants Hanuman a want that his system might be as robust as Indra's Vajra, Which his Vajra can also not harm him. As well as Indra other gods have also granted him needs: the God Agni granted Hanuman a want https://hindutemplesouthaustralia.politics.blog/2024/02/22/spiritual-journey-puja-at-hanuman-ji-mandir-south-australia/