Could not pass event PlayerJoinEvent to Essentials v1.0
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) ~[spigot-1.11.2.jar:git-Spigot-3fb9445-6e3cec8]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[spigot-1.11.2.jar:git-Spigot-3fb9445-6e3cec8]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:502) [spigot-1.11.2.jar:git-Spigot-3fb9445-6e3cec8]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:487) [spigot-1.11.2.jar:git-Spigot-3fb9445-6e3cec8]
        at net.minecraft.server.v1_11_R1.PlayerList.onPlayerJoin(PlayerList.java:327) [spigot-1.11.2.jar:git-Spigot-3fb9445-6e3cec8]
        at net.minecraft.server.v1_11_R1.PlayerList.a(PlayerList.java:160) [spigot-1.11.2.jar:git-Spigot-3fb9445-6e3cec8]
        at net.minecraft.server.v1_11_R1.LoginListener.b(LoginListener.java:147) [spigot-1.11.2.jar:git-Spigot-3fb9445-6e3cec8]
        at net.minecraft.server.v1_11_R1.LoginListener.F_(LoginListener.java:57) [spigot-1.11.2.jar:git-Spigot-3fb9445-6e3cec8]
        at net.minecraft.server.v1_11_R1.NetworkManager.a(NetworkManager.java:233) [spigot-1.11.2.jar:git-Spigot-3fb9445-6e3cec8]
        at net.minecraft.server.v1_11_R1.ServerConnection.c(ServerConnection.java:140) [spigot-1.11.2.jar:git-Spigot-3fb9445-6e3cec8]
        at net.minecraft.server.v1_11_R1.MinecraftServer.D(MinecraftServer.java:842) [spigot-1.11.2.jar:git-Spigot-3fb9445-6e3cec8]
        at net.minecraft.server.v1_11_R1.DedicatedServer.D(DedicatedServer.java:399) [spigot-1.11.2.jar:git-Spigot-3fb9445-6e3cec8]
        at net.minecraft.server.v1_11_R1.MinecraftServer.C(MinecraftServer.java:678) [spigot-1.11.2.jar:git-Spigot-3fb9445-6e3cec8]
        at net.minecraft.server.v1_11_R1.MinecraftServer.run(MinecraftServer.java:576) [spigot-1.11.2.jar:git-Spigot-3fb9445-6e3cec8]
        at java.base/java.lang.Thread.run(Thread.java:830) [?:?]
Caused by: java.lang.NullPointerException
        at de.essentials.main.PlayerJoin.onPlayerJoin(PlayerJoin.java:31) ~[?:?]
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?]
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:?]
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?]
        at java.base/java.lang.reflect.Method.invoke(Method.java:567) ~[?:?]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:302) ~[spigot-1.11.2.jar:git-Spigot-3fb9445-6e3cec8]
        ... 14 more