error-handling

Error handling for Node and NestJS backends - operational vs programmer errors, domain vs transport errors, custom error classes with codes, one global exception filter, RFC 9457 problem+json mapping, mapping domain, Prisma and upstream errors to HTTP statuses, logging once with correlation id, retries, timeouts and circuit breakers, errors in jobs, streams and SSE, process-level handlers, transaction rollback, Result-style returns, error code catalogue, and testing error paths. Load when adding failure paths, writing exception filters or error classes, mapping errors to responses, or debugging unhandled errors.