SOURCE

const promise1 =  new Promise((resolve, reject) => reject());
const promise2 = promise1.then(
    // null,
    // function () {
    //     return 123
    // },
    null,
    function () {
        return {
            get then() {
                throw new Error();
            }
        }
    }
)

promise2.then(
    () => {
        console.log('已完成');
    },
    () => {
        console.log('已拒绝');
    }
)