Only Or Another Type

type Only<I, J> = {
  [P in keyof I]: I[P]
} & {
  [P in keyof J]?: never
}
 
type OneOrAnother<I, J> = Only<I, J> | Only<J, I>;
 
type Username = {
  nome: string;
  username: string;
};
 
type Email = {
  email: string;
}
 
type User = OneOrAnother<Username, Email>
 
const user1: User = {
  email: ''
};
 
const user2: User = {
  username: '',
  nome: ''
};