feat: improve market category ID assignment in offer mapping logic

internal/ym/products/repository_api.go

@@ -185,12 +185,15 @@ func (r *apiRepository) processOfferMappings(offerMappings []ymclient.GetOfferMa
 		protoOffer := r.converter.YmOfferToProtoOffer(offerMapping.Offer)
 		if protoOffer == nil {
 			fmt.Printf("Warning: received nil offer for ID %s\n", offerMapping.Offer.OfferId)
-			resultOffers = append(resultOffers, &pb.GetProductsResponse_Offer{})
 			continue
 		}
-		protoOffer.MarketCategoryId = *offerMapping.Mapping.MarketCategoryId
-
+		if mapping, ok := offerMapping.GetMappingOk(); ok {
+			if marketCategoryId, ok := mapping.GetMarketCategoryIdOk(); ok {
+				protoOffer.MarketCategoryId = *marketCategoryId
+			}
+		}
 		resultOffers = append(resultOffers, protoOffer)
+
 	}
 
 	return resultOffers, nil