if (this.state === 'pending') {
            const p1 = new MyPromise((resolve, reject) => {
                this.resolveCallbacks.push(() => {
                    try {
                        const newValue = fn1(this.value)
                        resolve(newValue)
                    } catch (err) {
                        reject(err)
                    }
                })

                this.rejectCallbacks.push(() => {
                    try {
                        const newReason = fn2(this.reason)
                        reject(newReason)
                    } catch (err) {
                        reject(err)
                    }
                })
            })
            return p1
        }

当this.state === pending的时候，resolve(newValue)和reject(newReason)这两个函数不应该是在上一个promise中异步执行的吗，为什么产生的结果会添加到p1上呢