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Async without error handling

Nodemid

Main had a minimal registerUser — just password hash + DB insert. A colleague sent a PR adding welcome email, analytics, and batch user import. Production is already complaining: users register but don't get welcome emails. Walk the diff — hunt for async bugs.

PR: lesson.typescript +16 −04 проблем

11 import type { Request, Response } from 'express'

22 import { db } from './db'

3+import { sendEmail } from './email'

4+import { analytics } from './analytics'

46 export async function registerUser(req: Request, res: Response) {

57 const { email, password, name } = req.body

69 const hash = await hashPassword(password)

710 const user = await db.users.create({ email, passwordHash: hash, name })

11+

12+ sendEmail(user.email, 'Welcome!', `Hi ${user.name}`)

13+ analytics.track('user_registered', { userId: user.id })

14+

815 res.json({ success: true, userId: user.id })

916 }

1017

1118 export async function hashPassword(password: string): Promise<string> {

19+ // imagine bcrypt here

1220 return 'hash:' + password

1321 }

22+

23+export async function batchImportUsers(users: { email: string; name: string }[]) {

24+ users.forEach(async (u) => {

25+ const hash = await hashPassword('temp-password')

26+ await db.users.create({ email: u.email, passwordHash: hash, name: u.name })

27+ })

28+ console.log('Import done')

29+}

Шаг 1 из 6

Async patterns to hunt

In async code, hunt for: 1. **Function without try/catch** — in handlers and important operations, errors must be handled explicitly. 2. **Async call without await** — fire-and-forget: we don't wait, don't catch, don't know the status. 3. **`forEach` with an async callback** — forEach ignores the returned Promise; the result is unpredictable. 4. **A lost error inside Promise.all** — the first error rejects everything, others can be lost. Walk the code and try to find all four categories.