Planner: NullPointerException on calculateTimeGradient(HardAndSoftScoreDefinition.java:73) should have a better exception message: a construction heuristic is missing

2012-02-14 17:32:08,119 [main] INFO  Solver started: time spend (0), score (null), new best score (null), random seed (0). 
Exception in thread "main" java.lang.NullPointerException 
        at org.drools.planner.core.score.definition.HardAndSoftScoreDefinition.calculateTimeGradient(HardAndSoftScoreDefinition.java:73) 
        at org.drools.planner.core.score.definition.HardAndSoftScoreDefinition.calculateTimeGradient(HardAndSoftScoreDefinition.java:25) 
        at org.drools.planner.core.termination.ScoreAttainedTermination.calculateSolverTimeGradient(ScoreAttainedTermination.java:52) 
        at org.drools.planner.core.termination.OrCompositeTermination.calculateSolverTimeGradient(OrCompositeTermination.java:70) 
        at org.drools.planner.core.termination.OrCompositeTermination.calculateSolverTimeGradient(OrCompositeTermination.java:70) 
        at org.drools.planner.core.termination.PhaseToSolverTerminationBridge.calculatePhaseTimeGradient(PhaseToSolverTerminationBridge.java:49) 
        at org.drools.planner.core.localsearch.DefaultLocalSearchSolverPhase.solve(DefaultLocalSearchSolverPhase.java:55) 
        at org.drools.planner.core.solver.DefaultSolver.runSolverPhases(DefaultSolver.java:166) 
        at org.drools.planner.core.solver.DefaultSolver.solve(DefaultSolver.java:138) 
        at kz.bee.drools.planner.dating.DatingMain.start(DatingMain.java:58) 
        at kz.bee.drools.planner.dating.DatingMain.main(DatingMain.java:38)