Log And Return Duplication (ARCH5166)

Key go.logging.log-and-return-error · Severity warning · Category logging

Logging an error and then returning it from the same handler produces duplicate log lines, since the error is logged again as it propagates up the stack. An error should either be logged or returned wrapped - not both.

Incorrect

func fetch(log *slog.Logger, id string) (*Doc, error) {
  d, err := repo.Get(id)
  if err != nil {
    log.Error("fetch failed", "err", err)
    return nil, err
  }
  return d, nil
}

Correct

func fetch(id string) (*Doc, error) {
  d, err := repo.Get(id)
  if err != nil {
    return nil, fmt.Errorf("fetch %s: %w", id, err)
  }
  return d, nil
}

Fix

Return the error wrapped and log it only once at the top-level boundary layer.