🐛 bug: guard typed-nil errors

Author: gaby

app.go

@@ -30,6 +30,7 @@ import (
 	"github.com/valyala/fasthttp"
 
 	"github.com/gofiber/fiber/v3/binder"
+	"github.com/gofiber/fiber/v3/internal/nilerror"
 	"github.com/gofiber/fiber/v3/log"
 )
 
@@ -618,6 +619,10 @@ var httpReadResponse = http.ReadResponse
 
 // DefaultErrorHandler that process return errors from handlers
 func DefaultErrorHandler(c Ctx, err error) error {
+	if nilerror.IsNil(err) {
+		err = nil
+	}
+
 	code := StatusInternalServerError
 	var e *Error
 	matched := errors.As(err, &e)

app_test.go

@@ -37,6 +37,14 @@ import (
 	"github.com/valyala/fasthttp/fasthttputil"
 )
 
+type typedNilHandlerError struct {
+	message string
+}
+
+func (e *typedNilHandlerError) Error() string {
+	return e.message
+}
+
 type fileView struct {
 	path    string
 	content string
@@ -645,6 +653,21 @@ func Test_DefaultErrorHandler_TypedNilFiberError(t *testing.T) {
 	require.Equal(t, utils.StatusMessage(StatusInternalServerError), string(c.fasthttp.Response.Body()))
 }
 
+func Test_DefaultErrorHandler_TypedNilCustomError(t *testing.T) {
+	t.Parallel()
+
+	app := New()
+	c := app.AcquireCtx(&fasthttp.RequestCtx{}).(*DefaultCtx) //nolint:errcheck,forcetypeassert // not needed
+	t.Cleanup(func() { app.ReleaseCtx(c) })
+
+	var err *typedNilHandlerError
+	require.NotPanics(t, func() {
+		require.NoError(t, DefaultErrorHandler(c, err))
+	})
+	require.Equal(t, StatusInternalServerError, c.fasthttp.Response.StatusCode())
+	require.Equal(t, utils.StatusMessage(StatusInternalServerError), string(c.fasthttp.Response.Body()))
+}
+
 func Test_DefaultErrorHandler_WrappedFiberErrorUsesWrappedMessage(t *testing.T) {
 	t.Parallel()
 

bind.go

@@ -9,6 +9,7 @@ import (
 	"sync"
 
 	"github.com/gofiber/fiber/v3/binder"
+	"github.com/gofiber/fiber/v3/internal/nilerror"
 	"github.com/gofiber/schema"
 	"github.com/gofiber/utils/v2"
 	utilsbytes "github.com/gofiber/utils/v2/bytes"
@@ -158,7 +159,7 @@ func (b *Bind) SkipValidation(skip bool) *Bind {
 
 // Check WithAutoHandling/WithoutAutoHandling errors and return it by usage.
 func (b *Bind) returnErr(err error) error {
-	if err == nil {
+	if nilerror.IsNil(err) {
 		return nil
 	}
 

bind_test.go

@@ -25,6 +25,14 @@ import (
 
 const helloWorld = "hello world"
 
+type typedNilBindError struct {
+	message string
+}
+
+func (e *typedNilBindError) Error() string {
+	return e.message
+}
+
 // go test -run Test_returnErr -v
 func Test_returnErr(t *testing.T) {
 	app := New()
@@ -45,6 +53,19 @@ func Test_returnErr_TypedNilFiberError(t *testing.T) {
 	require.NoError(t, c.Bind().WithAutoHandling().returnErr(err))
 }
 
+func Test_returnErr_TypedNilCustomError(t *testing.T) {
+	t.Parallel()
+
+	app := New()
+	c := app.AcquireCtx(&fasthttp.RequestCtx{})
+	t.Cleanup(func() { app.ReleaseCtx(c) })
+
+	var err *typedNilBindError
+	require.NotPanics(t, func() {
+		require.NoError(t, c.Bind().WithAutoHandling().returnErr(err))
+	})
+}
+
 func Test_returnBindErr_TypedNilFiberError(t *testing.T) {
 	t.Parallel()
 

ctx_interface_gen.go

@@ -0,0 +1,20 @@
+package nilerror
+
+import (
+	"reflect"
+)
+
+// IsNil reports whether err is nil or contains a typed-nil value.
+func IsNil(err error) bool {
+	if err == nil {
+		return true
+	}
+
+	v := reflect.ValueOf(err)
+	switch v.Kind() {
+	case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Pointer, reflect.Slice:
+		return v.IsNil()
+	default:
+		return false
+	}
+}

internal/nilerror/nilerror.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 
 	"github.com/gofiber/fiber/v3"
+	"github.com/gofiber/fiber/v3/internal/nilerror"
 )
 
 const (
@@ -30,6 +31,10 @@ func New(config ...Config) fiber.Handler {
 
 // getEffectiveStatusCode returns the actual status code, considering both the error and response status
 func getEffectiveStatusCode(c fiber.Ctx, err error) int {
+	if nilerror.IsNil(err) {
+		return c.Response().StatusCode()
+	}
+
 	// If there's an error and it's a *fiber.Error, use its status code
 	var fiberErr *fiber.Error
 	if errors.As(err, &fiberErr) && fiberErr != nil {

middleware/limiter/limiter.go

@@ -26,6 +26,14 @@ type failingLimiterStorage struct {
 
 const testLimiterClientKey = "client-key"
 
+type typedNilLimiterError struct {
+	message string
+}
+
+func (e *typedNilLimiterError) Error() string {
+	return e.message
+}
+
 func newFailingLimiterStorage() *failingLimiterStorage {
 	return &failingLimiterStorage{
 		data: make(map[string][]byte),
@@ -211,6 +219,21 @@ func TestGetEffectiveStatusCodeTypedNilFiberError(t *testing.T) {
 	})
 }
 
+func TestGetEffectiveStatusCodeTypedNilCustomError(t *testing.T) {
+	t.Parallel()
+
+	app := fiber.New()
+	c := app.AcquireCtx(&fasthttp.RequestCtx{})
+	t.Cleanup(func() { app.ReleaseCtx(c) })
+
+	c.Response().SetStatusCode(fiber.StatusAccepted)
+
+	var err *typedNilLimiterError
+	require.NotPanics(t, func() {
+		require.Equal(t, fiber.StatusAccepted, getEffectiveStatusCode(c, err))
+	})
+}
+
 func TestLimiterFixedStorageGetError(t *testing.T) {
 	t.Parallel()