Gql-response READ_ONLY? Если да, то почему?

constructor(private apollo: Apollo) {}    

ngOnInit(){
    /* -- apollo query setup--- */             
    const subscriber = this.apollo.query<any>(this.options);
    subscriber.subscribe((data) => {
        data.data.id = 'demo'
    } 
}

Ошибка:

Uncaught (in promise): TypeError: Cannot assign to read only property 'id' of object '[object Object]' TypeError: Cannot assign to read only property 'id' of object '[object Object]'