revert: work backward compatible

app.go

@@ -84,9 +84,8 @@ type ErrorHandler = func(*Ctx, error) error
 
 // Error represents an error that occurred while handling a request.
 type Error struct {
-	Code       int         `json:"code"`
-	Message    string      `json:"message"`
-	AnyMessage interface{} `json:"-"`
+	Code    int    `json:"code"`
+	Message string `json:"message"`
 }
 
 // App denotes the Fiber application.
@@ -727,29 +726,13 @@ func (e *Error) Error() string {
 }
 
 // NewError creates a new Error instance with an optional message
-func NewError(code int, message ...interface{}) *Error {
+func NewError(code int, message ...string) *Error {
 	err := &Error{
-		Code:       code,
-		Message:    utils.StatusMessage(code),
-		AnyMessage: utils.StatusMessage(code),
+		Code:    code,
+		Message: utils.StatusMessage(code),
 	}
 	if len(message) > 0 {
-		err.Message = utils.ToString(message[0])
-		err.AnyMessage = message[0]
-	}
-	return err
-}
-
-// NewErrors creates multiple new Error messages
-func NewErrors(code int, messages ...interface{}) *Error {
-	err := &Error{
-		Code:       code,
-		Message:    utils.StatusMessage(code),
-		AnyMessage: utils.StatusMessage(code),
-	}
-	if len(messages) > 0 {
-		err.Message = utils.ToString(messages)
-		err.AnyMessage = messages
+		err.Message = message[0]
 	}
 	return err
 }

app_test.go

@@ -1235,14 +1235,6 @@ func Test_NewError(t *testing.T) {
 	utils.AssertEqual(t, "permission denied", err.Message)
 }
 
-func Test_NewErrors(t *testing.T) {
-	err := NewErrors(StatusBadRequest, "error 1", "error 2")
-	messages := err.AnyMessage.([]interface{})
-	utils.AssertEqual(t, StatusBadRequest, err.Code)
-	utils.AssertEqual(t, "error 1", fmt.Sprint(messages[0]))
-	utils.AssertEqual(t, "error 2", fmt.Sprint(messages[1]))
-}
-
 // go test -run Test_Test_Timeout
 func Test_Test_Timeout(t *testing.T) {
 	app := New()