As the error was done from the god Indra, he grants Hanuman a want that his human body will be as potent as Indra's Vajra, and that his Vajra could also not hurt him. As well as Indra other gods have also granted him needs: the God Agni granted Hanuman https://johnq986dnw7.bloggazzo.com/35863535/helping-the-others-realize-the-advantages-of-hanuman