Error /dxl group show

[benr233]

[01:59:43] [Server thread/ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'dxl' in plugin DungeonsXL v0.15.6
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46) ~[spigot-1.9.4.jar:git-Spigot-8a048fe-d8637df]
at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:141) ~[spigot-1.9.4.jar:git-Spigot-8a048fe-d8637df]
at org.bukkit.craftbukkit.v1_9_R2.CraftServer.dispatchCommand(CraftServer.java:646) ~[spigot-1.9.4.jar:git-Spigot-8a048fe-d8637df]
at net.minecraft.server.v1_9_R2.PlayerConnection.handleCommand(PlayerConnection.java:1349) [spigot-1.9.4.jar:git-Spigot-8a048fe-d8637df]
at net.minecraft.server.v1_9_R2.PlayerConnection.a(PlayerConnection.java:1184) [spigot-1.9.4.jar:git-Spigot-8a048fe-d8637df]
at net.minecraft.server.v1_9_R2.PacketPlayInChat.a(PacketPlayInChat.java:45) [spigot-1.9.4.jar:git-Spigot-8a048fe-d8637df]
at net.minecraft.server.v1_9_R2.PacketPlayInChat.a(PacketPlayInChat.java:1) [spigot-1.9.4.jar:git-Spigot-8a048fe-d8637df]
at net.minecraft.server.v1_9_R2.PlayerConnectionUtils$1.run(SourceFile:13) [spigot-1.9.4.jar:git-Spigot-8a048fe-d8637df]
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.8.0_131]
at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_131]
at net.minecraft.server.v1_9_R2.SystemUtils.a(SourceFile:45) [spigot-1.9.4.jar:git-Spigot-8a048fe-d8637df]
at net.minecraft.server.v1_9_R2.MinecraftServer.D(MinecraftServer.java:726) [spigot-1.9.4.jar:git-Spigot-8a048fe-d8637df]
at net.minecraft.server.v1_9_R2.DedicatedServer.D(DedicatedServer.java:399) [spigot-1.9.4.jar:git-Spigot-8a048fe-d8637df]
at net.minecraft.server.v1_9_R2.MinecraftServer.C(MinecraftServer.java:665) [spigot-1.9.4.jar:git-Spigot-8a048fe-d8637df]
at net.minecraft.server.v1_9_R2.MinecraftServer.run(MinecraftServer.java:564) [spigot-1.9.4.jar:git-Spigot-8a048fe-d8637df]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_131]
Caused by: java.lang.NullPointerException
at io.github.dre2n.dungeonsxl.player.DGroup.getDungeonName(DGroup.java:453) ~[?:?]
at io.github.dre2n.dungeonsxl.command.GroupCommand.showGroup(GroupCommand.java:264) ~[?:?]
at io.github.dre2n.dungeonsxl.command.GroupCommand.onExecute(GroupCommand.java:108) ~[?:?]
at io.github.dre2n.dungeonsxl.util.commons.command.BRCommandExecutor.onCommand(BRCommandExecutor.java:71) ~[?:?]
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[spigot-1.9.4.jar:git-Spigot-8a048fe-d8637df]
... 15 more