JumpChallenge v1.3 Error

[20:39:06 ERROR]: Could not pass event PlayerDropItemEvent to JumpChallenge v1.3
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) ~[spigot.jar:git-Spigot-570526c-c1b529e]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[spigot.jar:git-Spigot-570526c-c1b529e]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:502) [spigot.jar:git-Spigot-570526c-c1b529e]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:487) [spigot.jar:git-Spigot-570526c-c1b529e]
        at net.minecraft.server.v1_10_R1.EntityHuman.a(EntityHuman.java:565) [spigot.jar:git-Spigot-570526c-c1b529e]
        at net.minecraft.server.v1_10_R1.EntityHuman.drop(EntityHuman.java:521) [spigot.jar:git-Spigot-570526c-c1b529e]
        at net.minecraft.server.v1_10_R1.PlayerConnection.a(PlayerConnection.java:2044) [spigot.jar:git-Spigot-570526c-c1b529e]
        at net.minecraft.server.v1_10_R1.PacketPlayInSetCreativeSlot.a(SourceFile:23) [spigot.jar:git-Spigot-570526c-c1b529e]
        at net.minecraft.server.v1_10_R1.PacketPlayInSetCreativeSlot.a(SourceFile:9) [spigot.jar:git-Spigot-570526c-c1b529e]
        at net.minecraft.server.v1_10_R1.PlayerConnectionUtils$1.run(SourceFile:13) [spigot.jar:git-Spigot-570526c-c1b529e]
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.8.0_101]
        at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_101]
        at net.minecraft.server.v1_10_R1.SystemUtils.a(SourceFile:45) [spigot.jar:git-Spigot-570526c-c1b529e]
        at net.minecraft.server.v1_10_R1.MinecraftServer.D(MinecraftServer.java:732) [spigot.jar:git-Spigot-570526c-c1b529e]
        at net.minecraft.server.v1_10_R1.DedicatedServer.D(DedicatedServer.java:400) [spigot.jar:git-Spigot-570526c-c1b529e]
        at net.minecraft.server.v1_10_R1.MinecraftServer.C(MinecraftServer.java:668) [spigot.jar:git-Spigot-570526c-c1b529e]
        at net.minecraft.server.v1_10_R1.MinecraftServer.run(MinecraftServer.java:567) [spigot.jar:git-Spigot-570526c-c1b529e]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_101]
Caused by: java.lang.NullPointerException
        at de.NeonnBukkit.JumpChallenge.Listeners.onDrop(Listeners.java:211) ~[?:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_101]
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_101]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_101]
        at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_101]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:302) ~[spigot.jar:git-Spigot-570526c-c1b529e]
        ... 17 more