Fix button logic

server/server.js

@@ -312,24 +312,28 @@ app.post('/api/orders/:orderId/items', async (req, res) => {
 
 app.put('/api/orders/:orderId/items/:itemId', async (req, res) => {
     let itemId = req.params.itemId;
-    let quantity = req.body.quantity;
+    let { quantity, productId } = req.body;
+    quantity = Number.parseInt(quantity, 10);
     
     try {
         await adapter.updateOrderItem({
             itemId, 
+            productId,
             quantity
         });
         
         res.status(201).json({
             itemId, 
+            productId,
             quantity
         });
         
     } catch (err) {
-        res.json({
+        const statusCode = err.type === DB_USER_ERROR ? 400 : 500;
+        res.status(statusCode).json({
             timeStamp: new Date().toISOString(),
-            statusCode: 500,
-            error: err.message
+            statusCode,
+            error: err.error?.message || err.message
         });
     }
 });