As the mistake was done via the god Indra, he grants Hanuman a desire that his human body will be as powerful as Indra's Vajra, Which his Vajra might also not hurt him. Coupled with Indra other gods have also granted him needs: the God Agni granted Hanuman a wish https://directorypixels.com/listings13360241/top-latest-five-hanuman-urban-news