联合类型在对象初始化器中允许使用多余属性

可以使用类型断言或使用类型别名来解决此问题。例如，使用类型断言：

type Person = { name: string, age: number };

let person: Person | { address: string } = { name: "John", age: 30, address: "123 Main St" } as Person;

或者，使用类型别名：

type Person = { name: string, age: number };
type PersonWithAddress = Person & { address: string };

let person: PersonWithAddress = { name: "John", age: 30, address: "123 Main St" };