refactor(serialization): streamline custom validation logic in ValidateWithCustomValidator function

internal/serialization/serialization.go

@@ -89,31 +89,35 @@ func ValidateWithFieldTags(s any) gperr.Error {
 	return errs.Error()
 }
 
+var validatorType = reflect.TypeFor[CustomValidator]()
+
 func ValidateWithCustomValidator(v reflect.Value) gperr.Error {
-	isStruct := false
-	for {
-		switch v.Kind() {
-		case reflect.Pointer, reflect.Interface:
-			if v.IsNil() {
-				return gperr.Errorf("validate: v is %w", ErrNilValue)
-			}
-			if validate, ok := v.Interface().(CustomValidator); ok {
-				return validate.Validate()
-			}
-			if isStruct {
-				return nil
-			}
-			v = v.Elem()
-		case reflect.Struct:
-			if !v.CanAddr() {
-				return nil
-			}
-			v = v.Addr()
-			isStruct = true
-		default:
+	if v.Kind() == reflect.Struct {
+		if v.Type().Implements(validatorType) {
+			return v.Interface().(CustomValidator).Validate()
+		}
+		if v.CanAddr() {
+			return validateWithValidator(v.Addr())
+		}
+		return nil
+	}
+	if v.Kind() == reflect.Pointer {
+		if v.IsNil() {
 			return nil
 		}
+		if v.Type().Implements(validatorType) {
+			return v.Interface().(CustomValidator).Validate()
+		}
+		return validateWithValidator(v.Elem())
 	}
+	return nil
+}
+
+func validateWithValidator(v reflect.Value) gperr.Error {
+	if v.Type().Implements(validatorType) {
+		return v.Interface().(CustomValidator).Validate()
+	}
+	return nil
 }
 
 func dive(dst reflect.Value) (v reflect.Value, t reflect.Type, err gperr.Error) {