Fix mock tests

Former-commit-id: 3efa83bc44

src/main/java/auctiora/AuctionMonitorResource.java

@@ -495,19 +495,22 @@ public class AuctionMonitorResource {
                                ));
          }
          
-         // Add geographic insight
+         // Add geographic insight (filter out null countries)
          String topCountry = auctions.stream()
+                                     .filter(a -> a.country() != null)
                                      .collect(Collectors.groupingBy(AuctionInfo::country, Collectors.counting()))
                                      .entrySet().stream()
                                      .max(Map.Entry.comparingByValue())
                                      .map(Map.Entry::getKey)
                                      .orElse("N/A");
 
-         insights.add(Map.of(
-                 "icon", "fa-globe",
-                 "title", topCountry + " leading",
-                 "description", "Top performing country"
-                            ));
+         if (!"N/A".equals(topCountry)) {
+            insights.add(Map.of(
+                    "icon", "fa-globe",
+                    "title", topCountry + " leading",
+                    "description", "Top performing country"
+                               ));
+         }
 
          // Add sleeper lots insight
          long sleeperCount = lots.stream().filter(Lot::isSleeperLot).count();