error-handling

Structured error handling in Node.js with TypeScript is implemented using a base AppError class with status codes and a global middleware to format responses and log operational errors consistently.

Global error handling in Express and NestJS is set up by adding an Express error-handling middleware or a NestJS global exception filter to catch, format, and log errors uniformly.

Unhandled promise rejections in Node.js are handled by capturing the events and triggering a graceful shutdown of the server, database, cache, and background workers to prevent data corruption.

External service call failures are wrapped into consistent errors by using a helper function that catches failures and converts them into standardized AppError instances with appropriate status codes.

This error handling approach requires TypeScript and a logger to record operational errors, but it does not mandate a specific logging library, allowing integration with your existing logging setup.

Common gotchas when implementing custom error classes in Node.js include accidentally exposing stack traces to clients and improperly mixing operational errors with programming errors.