return 0 as total score when there is no lance

src/game/ScoreTable.java

@@ -14,6 +14,7 @@ public class ScoreTable {
 	}
 	
 	public int getCurrentScore() {
+		if (frames.size() == 0) return 0;
 		return frames.get(frames.size() - 1).getScore();
 	}