at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:487) [spigot.jar:git-Spigot-e4d4710-e1ebe52]
        at net.minecraft.server.v1_8_R3.PlayerConnection.a(PlayerConnection.java:1630) [spigot.jar:git-Spigot-e4d4710-e1ebe52]
        at net.minecraft.server.v1_8_R3.PacketPlayInWindowClick.a(SourceFile:31) [spigot.jar:git-Spigot-e4d4710-e1ebe52]
        at net.minecraft.server.v1_8_R3.PacketPlayInWindowClick.a(SourceFile:9) [spigot.jar:git-Spigot-e4d4710-e1ebe52]
        at net.minecraft.server.v1_8_R3.PlayerConnectionUtils$1.run(SourceFile:13) [spigot.jar:git-Spigot-e4d4710-e1ebe52]
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_212]
        at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_212]
        at net.minecraft.server.v1_8_R3.SystemUtils.a(SourceFile:44) [spigot.jar:git-Spigot-e4d4710-e1ebe52]
        at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:715) [spigot.jar:git-Spigot-e4d4710-e1ebe52]
        at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:374) [spigot.jar:git-Spigot-e4d4710-e1ebe52]
        at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:654) [spigot.jar:git-Spigot-e4d4710-e1ebe52]
        at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:557) [spigot.jar:git-Spigot-e4d4710-e1ebe52]
        at java.lang.Thread.run(Thread.java:748) [?:1.8.0_212]
Caused by: java.lang.NullPointerException
        at java.util.Objects.requireNonNull(Objects.java:203) ~[?:1.8.0_212]
        at java.util.Optional.<init>(Optional.java:96) ~[?:1.8.0_212]
        at java.util.Optional.of(Optional.java:108) ~[?:1.8.0_212]
        at java.util.stream.FindOps$FindSink$OfRef.get(FindOps.java:193) ~[?:1.8.0_212]
        at java.util.stream.FindOps$FindSink$OfRef.get(FindOps.java:190) ~[?:1.8.0_212]
        at java.util.stream.FindOps$FindOp.evaluateSequential(FindOps.java:152) ~[?:1.8.0_212]
        at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[?:1.8.0_212]
        at java.util.stream.ReferencePipeline.findFirst(ReferencePipeline.java:464) ~[?:1.8.0_212]
        at io.lucasdev.bukkit.listeners.InventoryListener.onInteract(InventoryListener.java:68) ~[?:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_212]
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_212]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_212]
        at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_212]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) ~[spigot.jar:git-Spigot-e4d4710-e1ebe52]