[9445] Possible fix often crashes in waypoint movegen.

Thanks to DrKLO for research source of problem!

src/game/TargetedMovementGenerator.cpp

@@ -149,6 +149,9 @@ bool TargetedMovementGeneratorMedium<T,D>::Update(T &owner, const uint32 & time_
 
     if (i_destinationHolder.UpdateTraveller(traveller, time_diff, false))
     {
+        if (!IsActive(owner))                               // force stop processing (movement can move out active zone with cleanup movegens list)
+            return true;                                    // not expire now, but already lost
+
         // put targeted movement generators on a higher priority
         if (owner.GetObjectSize())
             i_destinationHolder.ResetUpdate(50);