Define keys as null or optional

null-undefined.ts

// Define either undefined or null
type Maybe<T> = T | undefined | null;

type User = {
  name: string
  email: string
  phone: Maybe<string>
}

/**
type User = {
    name: string;
    email: string;
    phone: string | null | undefined;
}
 */

type Question = {
  value: string
  user: Maybe<User>
}

/**
type Question = {
    value: string;
    user: User | undefined | null;
}
 */