As the error was performed from the god Indra, he grants Hanuman a desire that his system would be as solid as Indra's Vajra, Which his Vajra can also not hurt him. In addition to Indra other gods have also granted him wishes: the God Agni granted Hanuman a want https://bajrangbalisouthindiantemples.blogspot.com/2024/12/discover-spiritual-peace-at-hanuman.html