Check for NULL = NULL Pointer Exception

[18:40:02 INFO]: 20b7b06f-2e0d-382b-9327-ba2e734cde7e
[18:40:02 ERROR]: Could not pass event InventoryClickEvent to GuiGame v0.0.1
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:305) ~[spigot.jar:git-Spigot-dbe012b-61ef214]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.jav
a:62) ~[spigot.jar:git-Spigot-dbe012b-61ef214]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.j
ava:502) [spigot.jar:git-Spigot-dbe012b-61ef214]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.j
ava:487) [spigot.jar:git-Spigot-dbe012b-61ef214]
        at net.minecraft.server.v1_8_R2.PlayerConnection.a(PlayerConnection.java
:1618) [spigot.jar:git-Spigot-dbe012b-61ef214]
        at net.minecraft.server.v1_8_R2.PacketPlayInWindowClick.a(SourceFile:31)
 [spigot.jar:git-Spigot-dbe012b-61ef214]
        at net.minecraft.server.v1_8_R2.PacketPlayInWindowClick.a(SourceFile:9)
[spigot.jar:git-Spigot-dbe012b-61ef214]
        at net.minecraft.server.v1_8_R2.PlayerConnectionUtils$1.run(SourceFile:1
3) [spigot.jar:git-Spigot-dbe012b-61ef214]
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [
?:1.8.0_31]
        at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_31]
        at net.minecraft.server.v1_8_R2.SystemUtils.a(SourceFile:60) [spigot.jar
:git-Spigot-dbe012b-61ef214]
        at net.minecraft.server.v1_8_R2.MinecraftServer.A(MinecraftServer.java:7
10) [spigot.jar:git-Spigot-dbe012b-61ef214]
        at net.minecraft.server.v1_8_R2.DedicatedServer.A(DedicatedServer.java:3
68) [spigot.jar:git-Spigot-dbe012b-61ef214]
        at net.minecraft.server.v1_8_R2.MinecraftServer.z(MinecraftServer.java:6
51) [spigot.jar:git-Spigot-dbe012b-61ef214]
        at net.minecraft.server.v1_8_R2.MinecraftServer.run(MinecraftServer.java
:554) [spigot.jar:git-Spigot-dbe012b-61ef214]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_31]
Caused by: java.lang.NullPointerException
        at com.storm28.guigame.CookieClicker.openCCGUI(CookieClicker.java:28) ~[
?:?]
        at com.storm28.guigame.GuiGameMain.onInventoryClick(GuiGameMain.java:162
) ~[?:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0
_31]
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0
_31]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1
.8.0_31]
        at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_31]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:301) ~[spigot.jar:git-Spigot-dbe012b-61ef214]
        ... 15 more