As the error was done via the god Indra, he grants Hanuman a desire that his physique would be as strong as Indra's Vajra, Which his Vajra may also not hurt him. Coupled with Indra other gods have also granted him wishes: the God Agni granted Hanuman a want that https://mua95177.canariblogs.com/details-fiction-and-hanuman-51845673