Error

15:07:56 [INFO] [Permissions] No world specified. Defaulting to default world.
15:07:56 [WARNING] Unexpected exception while parsing console command
org.bukkit.command.CommandException: Unhandled exception executing command 'pr' in plugin Permissions v3.1.6
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:37)
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:129)
        at org.bukkit.craftbukkit.CraftServer.dispatchCommand(CraftServer.java:312)
        at net.minecraft.server.MinecraftServer.b(MinecraftServer.java:480)
        at net.minecraft.server.MinecraftServer.h(MinecraftServer.java:465)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:361)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:422)
Caused by: java.lang.NullPointerException
        at java.util.HashSet.<init>(HashSet.java:116)
        at com.nijiko.data.YamlGroupStorage.getTracks(YamlGroupStorage.java:284)
        at com.nijiko.permissions.PermissionWorld.getTracks(PermissionWorld.java:168)
        at com.nijiko.permissions.ModularControl.getTracks(ModularControl.java:532)
        at com.nijikokun.bukkit.Permissions.Permissions.onCommand(Permissions.java:731)
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:35)
        ... 6 more