Bug fix in MDPRewardsSimple.

git-svn-id: https://www.prismmodelchecker.org/svn/prism/prism/trunk@3371 bbc10eb1-c90d-0410-af57-cb519fbb1720

prism/src/explicit/rewards/MDPRewardsSimple.java

@@ -106,6 +106,8 @@ public class MDPRewardsSimple implements MDPRewards
 	@Override
 	public double getStateReward(int s)
 	{
+		if (stateRewards == null)
+			return 0.0;
 		return stateRewards.get(s);
 	}