secured against disappearing legs and the resulting NPEs (bug 794)

java/com.sap.sailing.domain/src/com/sap/sailing/domain/tracking/impl/TrackedRaceImpl.java

@@ -588,7 +588,8 @@ public abstract class TrackedRaceImpl implements TrackedRace, CourseListener {
 
     @Override
     public TrackedLegOfCompetitor getTrackedLeg(Competitor competitor, Leg leg) {
-        return getTrackedLeg(leg).getTrackedLeg(competitor);
+        final TrackedLeg trackedLeg = getTrackedLeg(leg);
+        return trackedLeg == null ? null : trackedLeg.getTrackedLeg(competitor);
     }
 
     @Override

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

@@ -414,6 +414,9 @@ public class SailingServiceImpl extends RemoteServiceServlet implements SailingS
         if (addLegDetails && trackedRace != null) {
             entryDTO.legDetails = new ArrayList<LegEntryDTO>();
             for (Leg leg : trackedRace.getRace().getCourse().getLegs()) {
+                // We loop over a copy of the course's legs; during a course change, legs may become "stale," even with
+                // regard to the leg/trackedLeg structures inside the tracked race which is updated by the course change
+                // immediately. Make sure we're tolerant against disappearing legs! See bug 794.
                 TrackedLegOfCompetitor trackedLeg = trackedRace.getTrackedLeg(competitor, leg);
                 LegEntryDTO legEntry;
                 if (trackedLeg != null && trackedLeg.hasStartedLeg(timePoint)) {