fixing NPE in case polars for non-existing race are requested

java/com.sap.sailing.gwt.ui/src/main/java/com/sap/sailing/gwt/ui/server/SailingServiceImpl.java

@@ -1424,12 +1424,18 @@ public class SailingServiceImpl extends ProxiedRemoteServiceServlet implements S
 
     @Override
     public Boolean getPolarResults(RegattaAndRaceIdentifier raceIdentifier) {
+        final Boolean result;
         TrackedRace trackedRace = getExistingTrackedRace(raceIdentifier);
-        BoatClass boatClass = trackedRace.getRace().getBoatClass();
-        PolarDataService polarData = getService().getPolarDataService();
-        PolarDiagram polarDiagram = new PolarDiagramGPS(boatClass, polarData);
-        return new Boolean(polarDiagram != null);
-    };
+        if (trackedRace == null) {
+            result = false;
+        } else {
+            BoatClass boatClass = trackedRace.getRace().getBoatClass();
+            PolarDataService polarData = getService().getPolarDataService();
+            PolarDiagram polarDiagram = new PolarDiagramGPS(boatClass, polarData);
+            result = new Boolean(polarDiagram != null);
+        }
+        return result;
+    }
 
     @Override
     public SimulatorResultsDTO getSimulatorResults(RegattaAndRaceIdentifier raceIdentifier, Date from, Date prevStartTime) {