Bukkit

[SEVERE] Could not pass event PlayerCommandPreprocessEvent to BetterAlias v1.3
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:427)
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:462)
        at net.minecraft.server.v1_6_R2.PlayerConnection.handleCommand(PlayerConnection.java:956)
        at net.minecraft.server.v1_6_R2.PlayerConnection.chat(PlayerConnection.java:882)
        at org.bukkit.craftbukkit.v1_6_R2.entity.CraftPlayer.chat(CraftPlayer.java:237)
        at com.ne0nx3r0.betteralias.alias.AliasManager.sendAliasCommands(AliasManager.java:402)
        at com.ne0nx3r0.betteralias.listener.BetterAliasCommandListener.onPlayerCommandPreprocess(BetterAliasCommandListener.java:47)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:477)
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:462)
        at net.minecraft.server.v1_6_R2.PlayerConnection.handleCommand(PlayerConnection.java:956)
        at net.minecraft.server.v1_6_R2.PlayerConnection.chat(PlayerConnection.java:882)
        at net.minecraft.server.v1_6_R2.PlayerConnection.a(PlayerConnection.java:839)
        at net.minecraft.server.v1_6_R2.Packet3Chat.handle(SourceFile:49)
        at net.minecraft.server.v1_6_R2.NetworkManager.b(NetworkManager.java:296)
        at net.minecraft.server.v1_6_R2.PlayerConnection.e(PlayerConnection.java:118)
        at net.minecraft.server.v1_6_R2.ServerConnection.b(SourceFile:37)
        at net.minecraft.server.v1_6_R2.DedicatedServerConnection.b(SourceFile:30)
        at net.minecraft.server.v1_6_R2.MinecraftServer.t(MinecraftServer.java:590)
        at net.minecraft.server.v1_6_R2.DedicatedServer.t(DedicatedServer.java:226)
        at net.minecraft.server.v1_6_R2.MinecraftServer.s(MinecraftServer.java:486)
        at net.minecraft.server.v1_6_R2.MinecraftServer.run(MinecraftServer.java:419)
        at net.minecraft.server.v1_6_R2.ThreadServerApplication.run(SourceFile:582)
Caused by: java.lang.NullPointerException
        at com.ne0nx3r0.betteralias.listener.BetterAliasCommandListener.onPlayerCommandPreprocess(BetterAliasCommandListener.java:30)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:601)
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:425)
        ... 29 more