인프런 커뮤니티 질문&답변

제가 강의를 따라하면서 코드를 아래처럼 작성했습니다

interface PhoneNumberDictionary {
  [home: string]: {
    num: number;
  };
}

interface Contact {
  name: string;
  address: string;
  phones: PhoneNumberDictionary;
}

// api
// TODO: 아래 함수의 반환 타입을 지정해보세요.
function fetchContacts(): Promise<Contact[]> {
  // TODO: 아래 변수의 타입을 지정해보세요.
  const contacts = [
    {
      name: "Tony",
      address: "Malibu",
      phones: {
        home: {
          num: 11122223333,
        },
        office: {
          num: 44455556666,
        },
      },
    },
    {
      name: "Banner",
      address: "New York",
      phones: {
        home: {
          num: 77788889999,
        },
      },
    },
    {
      name: "마동석",
      address: "서울시 강남구",
      phones: {
        home: {
          num: 213423452,
        },
        studio: {
          num: 314882045,
        },
      },
    },
  ];
  return new Promise((resolve) => {
    setTimeout(() => resolve(contacts), 2000);
  });
}

 setTimeout(() => resolve(contacts), 2000);

여기서 contacts에서 에러가 나는데 

Argument of type '({ name: string; address: string; phones: { home: { num: number; }; office: { num: number; }; studio?: undefined; }; } | { name: string; address: string; phones: { home: { num: number; }; office?: undefined; studio?: undefined; }; } | { ...; })[]' is not assignable to parameter of type 'Contact[] | PromiseLike<Contact[]>'.
  Type '({ name: string; address: string; phones: { home: { num: number; }; office: { num: number; }; studio?: undefined; }; } | { name: string; address: string; phones: { home: { num: number; }; office?: undefined; studio?: undefined; }; } | { ...; })[]' is not assignable to type 'Contact[]'.
    Type '{ name: string; address: string; phones: { home: { num: number; }; office: { num: number; }; studio?: undefined; }; } | { name: string; address: string; phones: { home: { num: number; }; office?: undefined; studio?: undefined; }; } | { ...; }' is not assignable to type 'Contact'.
      Type '{ name: string; address: string; phones: { home: { num: number; }; office: { num: number; }; studio?: undefined; }; }' is not assignable to type 'Contact'.
        Types of property 'phones' are incompatible.
          Type '{ home: { num: number; }; office: { num: number; }; studio?: undefined; }' is not assignable to type 'PhoneNumberDictionary'.
            Property 'studio' is incompatible with index signature.
              Type 'undefined' is not assignable to type '{ num: number; }'.ts(2345)

라고 뜹니다

제가 잘못 따라한게 있을가요?