[15:26:00 ERROR]: Could not pass event AsyncPlayerChatEvent to mcown v4.5.2

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:484) [Spigot.jar:git-Spigot-db6de12-18fbb24]

at net.minecraft.server.v1_8_R3.PlayerConnection.chat(PlayerConnection.java:1084) [Spigot.jar:git-Spigot-db6de12-18fbb24]

at net.minecraft.server.v1_8_R3.PlayerConnection.a(PlayerConnection.java:1022) [Spigot.jar:git-Spigot-db6de12-18fbb24]

at net.minecraft.server.v1_8_R3.PacketPlayInChat$1.run(PacketPlayInChat.java:39) [Spigot.jar:git-Spigot-db6de12-18fbb24]

at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_241]

at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_241]

at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_241]

at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_241]

at java.lang.Thread.run(Thread.java:748) [?:1.8.0_241]

Caused by: java.util.IllegalFormatConversionException: a != org.bukkit.craftbukkit.v1_8_R3.entity.CraftPlayer

at org.bukkit.event.player.AsyncPlayerChatEvent.setFormat(AsyncPlayerChatEvent.java:100) ~[Spigot.jar:git-Spigot-db6de12-18fbb24]

at de.mcown.items.JoinEvent.Prefix(JoinEvent.java:167) ~[?:?]

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_241]

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_241]

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_241]

at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_241]

at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) ~[Spigot.jar:git-Spigot-db6de12-18fbb24]

... 11 more