Console

[18:46:38 ERROR]: Could not pass event PlayerInteractEvent to Beginner v1.0
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:310) ~[spigot.jar:git-Spigot-db6de12-18fbb24]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[spigot.jar:git-Spigot-db6de12-18fbb24]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:502) [spigot.jar:git-Spigot-db6de12-18fbb24]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:487) [spigot.jar:git-Spigot-db6de12-18fbb24]
        at org.bukkit.craftbukkit.v1_8_R3.event.CraftEventFactory.callPlayerInteractEvent(CraftEventFactory.java:228) [spigot.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.PlayerInteractManager.interact(PlayerInteractManager.java:463) [spigot.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.PlayerConnection.a(PlayerConnection.java:759) [spigot.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.PacketPlayInBlockPlace.a(PacketPlayInBlockPlace.java:52) [spigot.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.PacketPlayInBlockPlace.a(PacketPlayInBlockPlace.java:1) [spigot.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.PlayerConnectionUtils$1.run(SourceFile:13) [spigot.jar:git-Spigot-db6de12-18fbb24]
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.8.0_201]
        at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_201]
        at net.minecraft.server.v1_8_R3.SystemUtils.a(SourceFile:44) [spigot.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:715) [spigot.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:374) [spigot.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:654) [spigot.jar:git-Spigot-db6de12-18fbb24]
        at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:557) [spigot.jar:git-Spigot-db6de12-18fbb24]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_201]
Caused by: java.lang.Error: Unresolved compilation problems:
        void is an invalid type for the variable handleNaviGUIClick
        Syntax error on token "(", ; expected
        Duplicate local variable event
        Syntax error on token ")", ; expected

        at de.mittelego.lernen.elements.Navi.handleNaviOpener(Navi.java:32) ~[?:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_201]
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_201]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_201]
        at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_201]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) ~[spigot.jar:git-Spigot-db6de12-18fbb24]
        ... 17 more