Handling NestJS Exceptions

When to use

• Adding new error types
• Fixing inconsistent error responses
• Removing scattered try/catch in controllers

Core rules

1. Single global exception filter catches all AppError subclasses
2. Result<T,E> mapped to HTTP via helper, not scattered try/catch
3. All errors extend AppError with statusCode
4. No try/catch in controllers; let exceptions bubble to filter

Reference shape (TypeScript)