Handled a crash condition when no plate candidates score above the minimum threshold

src/openalpr/result_aggregator.cpp

@@ -220,6 +220,8 @@ namespace alpr
           }
         }
         
+        if (sorted_results.size() > 0)
+        {
           // Figure out the best region for this cluster
           ResultRegionScore regionResults = findBestRegion(clusters[unique_plate_idx]);
 
@@ -243,6 +245,7 @@ namespace alpr
           }
           
           response.results.plates.push_back(copyResult);
+        }
 
       }
     }