Prism /pr preview cancel

2013-03-26 18:03:42 [SEVERE] null
org.bukkit.command.CommandException: Unhandled exception executing command 'prism' in plugin Prism v1.5.6
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46)
at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:187)
at org.bukkit.craftbukkit.v1_5_R2.CraftServer.dispatchCommand(CraftServer.java:523)
at net.minecraft.server.v1_5_R2.PlayerConnection.handleCommand(PlayerConnection.java:966)
at net.minecraft.server.v1_5_R2.PlayerConnection.chat(PlayerConnection.java:884)
at net.minecraft.server.v1_5_R2.PlayerConnection.a(PlayerConnection.java:841)
at net.minecraft.server.v1_5_R2.Packet3Chat.handle(Packet3Chat.java:44)
at net.minecraft.server.v1_5_R2.NetworkManager.b(NetworkManager.java:292)
at net.minecraft.server.v1_5_R2.PlayerConnection.d(PlayerConnection.java:110)
at net.minecraft.server.v1_5_R2.ServerConnection.b(SourceFile:35)
at net.minecraft.server.v1_5_R2.DedicatedServerConnection.b(SourceFile:30)
at net.minecraft.server.v1_5_R2.MinecraftServer.r(MinecraftServer.java:578)
at net.minecraft.server.v1_5_R2.DedicatedServer.r(DedicatedServer.java:225)
at net.minecraft.server.v1_5_R2.MinecraftServer.q(MinecraftServer.java:474)
at net.minecraft.server.v1_5_R2.MinecraftServer.run(MinecraftServer.java:407)
at net.minecraft.server.v1_5_R2.ThreadServerApplication.run(SourceFile:573)
Caused by: java.lang.NullPointerException
at me.botsko.prism.appliers.Preview.cancel_preview(Preview.java:145)
at me.botsko.prism.commands.PreviewCommand.handle(PreviewCommand.java:65)
at me.botsko.prism.commandlibs.Executor.onCommand(Executor.java:107)
at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44)
... 15 more

2013-03-26 18:05:26 [INFO] Prism version 1.5.6
2013-03-26 18:05:26 [INFO] Website: http://discover-prism.com
2013-03-26 18:05:26 [INFO] Author: viveleroi
2013-03-26 18:05:30 [INFO] /67.43.7.19:56933 lost connection