fix(ui): resolve dark mode layout gray colors in light-mode browser and fix row index looping on paginated tables

backend/server.js

@@ -122,6 +122,19 @@ app.get('/api/health', (req, res) => {
   });
 });
 
+// ─── Global JSON Error Handler ────────────────────────────────────────────────
+// Menangkap semua error yang tidak di-handle (termasuk multer, mongoose, dll.)
+// dan memastikan response selalu JSON, BUKAN HTML default Express.
+// eslint-disable-next-line no-unused-vars
+app.use((err, req, res, next) => {
+  console.error('[Global Error Handler]', err.message || err);
+  const status = err.status || err.statusCode || 500;
+  res.status(status).json({
+    error: err.message || 'Internal server error',
+    code: err.code || undefined,
+  });
+});
+
 // ─── Start Server ─────────────────────────────────────────────────────────────
 // Bind to 127.0.0.1 in production to prevent direct external access to port 3001.
 // All external traffic must go through the reverse proxy (Apache/Nginx) at port 80/443.