Starterquiz errors

29.02 12:10:09 [Server] INFO 	... 12 more
29.02 12:10:09 [Server] INFO 	at org.bukkit.command.PluginCommand.execute(PluginCommand.java:40)
29.02 12:10:09 [Server] INFO 	at me.sluijsens.StartersQuiz.CmdExecutor.onCommand(CmdExecutor.java:55)
29.02 12:10:09 [Server] INFO 	at me.sluijsens.StartersQuiz.QuizHandler.start(QuizHandler.java:42)
29.02 12:10:09 [Server] INFO 	at me.sluijsens.StartersQuiz.StartersQuiz.checkDone(StartersQuiz.java:223)
29.02 12:10:09 [Server] INFO Caused by: java.lang.NullPointerException
29.02 12:10:09 [Server] INFO 	at net.minecraft.server.ThreadServerApplication.run(SourceFile:465)
29.02 12:10:09 [Server] INFO 	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:435)
29.02 12:10:09 [Server] INFO 	at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:537)
29.02 12:10:09 [Server] INFO 	at net.minecraft.server.NetworkListenThread.a(NetworkListenThread.java:78)
29.02 12:10:09 [Server] INFO 	at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:100)
29.02 12:10:09 [Server] INFO 	at net.minecraft.server.NetworkManager.b(NetworkManager.java:226)
29.02 12:10:09 [Server] INFO 	at net.minecraft.server.Packet3Chat.handle(Packet3Chat.java:33)
29.02 12:10:09 [Server] INFO 	at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:725)
29.02 12:10:09 [Server] INFO 	at net.minecraft.server.NetServerHandler.chat(NetServerHandler.java:737)
29.02 12:10:09 [Server] INFO 	at net.minecraft.server.NetServerHandler.handleCommand(NetServerHandler.java:777)
29.02 12:10:09 [Server] INFO 	at org.bukkit.craftbukkit.CraftServer.dispatchCommand(CraftServer.java:457)
29.02 12:10:09 [Server] INFO 	at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:168)
29.02 12:10:09 [Server] INFO 	at org.bukkit.command.PluginCommand.execute(PluginCommand.java:42)
29.02 12:10:09 [Server] INFO org.bukkit.command.CommandException: Unhandled exception executing command 'sqstart' in plugin StartersQuiz v2.0