fix(backend): improve OFF API error handling

- Validate response is JSON before parsing (OFF returns HTML on 503)
- Don't cache empty results to avoid blocking future searches
- Add validateStatus to only accept 200 responses
- Better logging for API failures

apps/backend/off-service.js

@@ -62,23 +62,31 @@ export async function searchBabyProducts(query) {
         action: 'process',
       },
       timeout: 10000,
+      validateStatus: (status) => status === 200,
     });
 
-    if (response.data && response.data.products) {
+    // Check if response is actually JSON (OFF sometimes returns HTML on error)
+    if (typeof response.data === 'string' || !response.data.products) {
+      console.warn(`[OFF] Invalid response for "${searchTerm}": API may be down`);
+      return [];
+    }
+
     const products = response.data.products
       .map(transformOFFProduct)
       .filter(Boolean);
 
+    // Only cache non-empty results to avoid caching API failures
+    if (products.length > 0) {
       try {
         await redisClient.setEx(cacheKey, CACHE_TTL, JSON.stringify(products));
         console.log(`Cached ${products.length} OFF products for: ${searchTerm}`);
       } catch (cacheErr) {
         // cache write failed, still return the data
       }
-      return products;
+    } else {
+      console.log(`[OFF] No products found for "${searchTerm}", not caching empty result`);
     }
-
+    return products;
-    return [];
   } catch (error) {
     console.error('Error searching baby products from OFF:', error.message);
     return [];