JS interview in 2 minutes / Promise

class MyPromise {    dataHandlers = []    errorHandler = []    finalHandlers = []    constructor(func) {        // Apply handlers one by one and initialize every following handler with the previouses result        let onResolve = data => this.dataHandlers.reduce(            (acc, onData) => onData(acc),             data        )        // Just call every onReject        let onReject = error => this.errorHandler.reduce(            (_, onError) => onError(error),            undefined        )        // Just call every onFinal        let onFinal = () => this.finalHandlers.reduce(            (_, onFinal) => onFinal(),             undefined        )        // We need to set timeout, so our function        // executed after we set .then, .catch, and .finally        setTimeout(() => {            try {                func(onResolve, onReject)            } catch (error) {                onReject(error)            } finally {                onFinal()            }        }, 0)    }    then(onData, onError) {        if (onData) { this.dataHandlers.push(onData) }        if (onError) { this.errorHandler.push(onError) }        return this    }    catch(onError) {        return this.then(undefined, onError)    }    finally(onFinal) {        if (onFinal) { this.finalHandlers.push(onFinal) }        return this    }}

let dataPromise = new MyPromise((resolve, reject) => resolve(2))dataPromise    .then(res => res + 2)    .then(res => res * 2)    .then(res => console.log(res)) // 8    .finally(() => console.log('Finally!')) // Finally!    .finally(() => console.log('Finally (1)!')) // Finally (1)!let rejectPromise = new MyPromise((resolve, reject) => reject(2))rejectPromise    .then(res => res + 2)    .then(res => res * 2)    .then(res => console.log(res))    .catch(error => console.error(error)) // 2    .finally(() => console.log('Finally!')) // Finally!let throwErrorPromise = new MyPromise((resolve, reject) => { throw new Error('hello') })throwErrorPromise    .then(res => res + 2)    .then(res => res * 2)    .then(res => console.log(res))    .catch(error => console.error(error)) // hello    .finally(() => console.log('Finally!')) // Finally// This one will produce two errors instead of one.// Can you come up with the fix?let doubleErrorPromise = new MyPromise((resolve, reject) => reject('first'))doubleErrorPromise    .catch(error => { console.error(error); throw 'second' })// 'first'// 'second'// Uncaught 'second'// This is how it should worklet fixedDoubleErrorPromise = new Promise((resolve, reject) => reject('first'))fixedDoubleErrorPromise    .catch(error => { console.error(error); throw 'second' })// 'first'// Uncaught 'second'