Handling Errors TypeScript

When to use

• Creating new error types for a feature
• Mapping internal errors to HTTP responses
• Reviewing try/catch usage to eliminate swallowed errors

Core rules

1. All errors extend AppError base class
2. Expected business failures: return Result<T,E> (don't throw)
3. Unexpected errors (programmer errors, infra outages): throw only these
4. Never swallow errors: no empty catch, no console.log(e)
5. All catch blocks must handle or rethrow explicitly
6. Error types: BusinessError, NotFoundError, ValidationError, UnauthorizedError, ForbiddenError, ConflictError, InfrastructureError

Reference shape (TypeScript)