Latest Version, Command Is Error, Sometimes Works, Sometimes Not.

[Zhaaaaaaaaa]

[10.06 02:13:05] [Server] [Server thread/WARN] [minecraft/CommandHandler]: Couldn't process command: name all hide
[10.06 02:13:05] [Server] java.lang.NullPointerExceptionnull
[10.06 02:13:05] [Server] at com.tlf.HN.common.HideNames.setAll(HideNames.java:261) ~[HideNames.class:?]
[10.06 02:13:05] [Server] at com.tlf.HN.commands.CommandName.func_184881_a(CommandName.java:99) ~[CommandName.class:?]
[10.06 02:13:05] [Server] at net.minecraft.command.CommandHandler.func_175786_a(CommandHandler.java:119) [bj.class:?]
[10.06 02:13:05] [Server] at net.minecraft.command.CommandHandler.func_71556_a(CommandHandler.java:91) [bj.class:?]
[10.06 02:13:05] [Server] at net.minecraft.network.NetHandlerPlayServer.func_147361_d(NetHandlerPlayServer.java:962) [pa.class:?]
[10.06 02:13:05] [Server] at net.minecraft.network.NetHandlerPlayServer.func_147354_a(NetHandlerPlayServer.java:941) [pa.class:?]
[10.06 02:13:05] [Server] at net.minecraft.network.play.client.CPacketChatMessage.func_148833_a(SourceFile:37) [la.class:?]
[10.06 02:13:05] [Server] at net.minecraft.network.play.client.CPacketChatMessage.func_148833_a(SourceFile:9) [la.class:?]
[10.06 02:13:05] [Server] at net.minecraft.network.PacketThreadUtil$1.run(SourceFile:13) [hv$1.class:?]
[10.06 02:13:05] [Server] at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_271]
[10.06 02:13:05] [Server] at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_271]
[10.06 02:13:05] [Server] at net.minecraft.util.Util.func_181617_a(SourceFile:46) [h.class:?]
[10.06 02:13:05] [Server] at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:723) [MinecraftServer.class:?]
[10.06 02:13:05] [Server] at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:397) [nz.class:?]
[10.06 02:13:05] [Server] at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:668) [MinecraftServer.class:?]
[10.06 02:13:05] [Server] at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:526) [MinecraftServer.class:?]
[10.06 02:13:05] [Server] at java.lang.Thread.run(Thread.java:748) [?:1.8.0_271]

I do /name hide all
or /names hide all
"An unknown error occurred while attempting to perform this command"
Sometimes works, sometimes doesn't.