**FastAPI** uses it so that, if you use a Pydantic model in `response_model`, and your data has an error, you will see the error in your log.

But the client/user will not see it. Instead, the client will receive an "Internal Server Error" with an HTTP status code `500`.

			switch {
			case testCase.expectedErr == nil:
				if err != nil {
					t.Errorf("error: expected = <nil>, got = %v", err)
				}
			case err == nil:
				t.Errorf("error: expected = %v, got = <nil>", testCase.expectedErr)
			case testCase.expectedErr.Error() != err.Error():
				t.Errorf("error: expected = %v, got = %v", testCase.expectedErr, err)
			}
		})
	}
}

}

// IsErrIgnored returns whether given error is ignored or not.
func IsErrIgnored(err error, ignoredErrs ...error) bool {
	return IsErr(err, ignoredErrs...)
}

// IsErr returns whether given error is exact error.
func IsErr(err error, errs ...error) bool {
	for _, exactErr := range errs {
		if errors.Is(err, exactErr) {
			return true
		}
	}
	return false
}

	return json.Marshal(formatV3)
}

// countErrs - count a specific error.
func countErrs(errs []error, err error) int {
	i := 0
	for _, err1 := range errs {
		if err1 == err || errors.Is(err1, err) {
			i++
		}
	}
	return i
}

// Does all errors indicate we need to initialize all disks?.
func shouldInitErasureDisks(errs []error) bool {
	return countErrs(errs, errUnformattedDisk) == len(errs)
}

	userIdentities := make([]UserIdentity, len(users))
	g := errgroup.WithNErrs(len(users))

	for index := range users {
		g.Go(func() error {
			userName := path.Dir(users[index])
			user, err := iamOS.loadUserIdentity(ctx, userName, userType)
			if err != nil && !errors.Is(err, errNoSuchUser) {
				return fmt.Errorf("unable to load the user `%s`: %w", userName, err)
			}

	return db.callbacks
}

// AddError add error to db
func (db *DB) AddError(err error) error {
	if err != nil {
		if db.Config.TranslateError {
			if errTranslator, ok := db.Dialector.(ErrorTranslator); ok {
				err = errTranslator.Translate(err)
			}
		}

		if db.Error == nil {
			db.Error = err
		} else {
			db.Error = fmt.Errorf("%v; %w", db.Error, err)
		}
	}
	return db.Error
}

}

func authZLogIf(ctx context.Context, err error, errKind ...any) {
	logger.LogIf(ctx, "authZ", err, errKind...)
}

func peersLogIf(ctx context.Context, err error, errKind ...any) {
	if !errors.Is(err, grid.ErrDisconnected) {
		logger.LogIf(ctx, "peers", err, errKind...)
	}
}

func peersLogAlwaysIf(ctx context.Context, err error, errKind ...any) {
	if !errors.Is(err, grid.ErrDisconnected) {

type concErr struct {
	errMap     map[string]error
	summaryErr error
}

func (c concErr) Error() string {
	if c.summaryErr != nil {
		return c.summaryErr.Error()
	}
	return "<nil>"
}

func (c concErr) Unwrap() error {
	return c.summaryErr
}

func (c *SiteReplicationSys) toErrorFromErrMap(errMap map[string]error, actionName string) error {
	if len(errMap) == 0 {
		return nil

		if err != nil {
			iamLogIf(GlobalContext, fmt.Errorf("error parsing role ARN %s: %v", roleArn, err))
			return false
		}
		policies = newMappedPolicy(sys.rolesMap[arn]).toSlice()

	default:
		// Otherwise, inherit parent user's policy
		var err error
		policies, err = sys.PolicyDBGet(parentUser, args.Groups...)
		if err != nil {
			iamLogIf(GlobalContext, fmt.Errorf("error fetching policies on %s: %v", parentUser, err))

			if testCase.expectedError.Error() != actualErr.Error() {
				t.Errorf("Test %d: %s: Expected to fail with error \"%s\", but instead failed with error \"%s\" instead.", i+1, instanceType, testCase.expectedError.Error(), actualErr.Error())
			}
		}
		// Test passes as expected, but the output values are verified for correctness here.
		if actualErr == nil && testCase.shouldPass {