feat(i18n): apply ORY bypass whitelist policy and add error-code tests

backend/cmd/server/main.go

@@ -7,11 +7,9 @@ import (
 	"baron-sso-backend/internal/idp"
 	"baron-sso-backend/internal/logger"
 	"baron-sso-backend/internal/middleware"
-	"baron-sso-backend/internal/response"
 	"baron-sso-backend/internal/repository"
 	"baron-sso-backend/internal/service"
 	"baron-sso-backend/internal/validator"
-	"errors"
 	"fmt"
 	"log"
 	"log/slog"
@@ -272,34 +270,7 @@ func main() {
 		AppName:               "Baron SSO Backend",
 		DisableStartupMessage: true,  // Clean logs
 		ReadBufferSize:        32768, // 32KB로 증가 (긴 OIDC 챌린지 대응)
-		// Global Error Handler for Production Masking
-		ErrorHandler: func(c *fiber.Ctx, err error) error {
-			// Default status code
-			code := fiber.StatusInternalServerError
-
-			// Check if it's a known fiber.Error
-			var e *fiber.Error
-			if errors.As(err, &e) {
-				code = e.Code
-			}
-
-			// In production or stage, mask detailed 500+ errors
-			if appEnv == "production" || appEnv == "stage" {
-				if code >= 500 {
-					// Log the actual error for developers
-					slog.Error("Internal Server Error",
-						"error", err.Error(),
-						"path", c.Path(),
-						"method", c.Method(),
-					)
-					// Return masked message
-					return response.Error(c, code, response.StatusCode(code), "Internal Server Error")
-				}
-			}
-
-			// For development or non-500 errors, return the actual error message
-			return response.Error(c, code, response.StatusCode(code), err.Error())
-		},
+		ErrorHandler:          newErrorHandler(appEnv),
 	})
 
 	// Middleware