java.lang.IllegalStateException: Asynchronous entity add!
	at org.spigotmc.AsyncCatcher.catchOp(AsyncCatcher.java:14) ~[spigot-latest.jar:git-Spigot-2086bb0-d0a3620]
	at net.minecraft.server.v1_12_R1.World.addEntity(World.java:1017) ~[spigot-latest.jar:git-Spigot-2086bb0-d0a3620]
	at net.minecraft.server.v1_12_R1.WorldServer.addEntity(WorldServer.java:1115) ~[spigot-latest.jar:git-Spigot-2086bb0-d0a3620]
	at net.minecraft.server.v1_12_R1.World.addEntity(World.java:1013) ~[spigot-latest.jar:git-Spigot-2086bb0-d0a3620]
	at net.minecraft.server.v1_12_R1.EntityHuman.a(EntityHuman.java:566) ~[spigot-latest.jar:git-Spigot-2086bb0-d0a3620]
	at net.minecraft.server.v1_12_R1.EntityHuman.a(EntityHuman.java:551) ~[spigot-latest.jar:git-Spigot-2086bb0-d0a3620]
	at net.minecraft.server.v1_12_R1.EntityHuman.drop(EntityHuman.java:490) ~[spigot-latest.jar:git-Spigot-2086bb0-d0a3620]
	at net.minecraft.server.v1_12_R1.CommandGive.execute(SourceFile:75) ~[spigot-latest.jar:git-Spigot-2086bb0-d0a3620]
	at org.bukkit.craftbukkit.v1_12_R1.command.VanillaCommandWrapper.dispatchVanillaCommand(VanillaCommandWrapper.java:109) [spigot-latest.jar:git-Spigot-2086bb0-d0a3620]
	at org.bukkit.craftbukkit.v1_12_R1.command.VanillaCommandWrapper.execute(VanillaCommandWrapper.java:38) [spigot-latest.jar:git-Spigot-2086bb0-d0a3620]
	at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:141) [spigot-latest.jar:git-Spigot-2086bb0-d0a3620]
	at org.bukkit.craftbukkit.v1_12_R1.CraftServer.dispatchCommand(CraftServer.java:648) [spigot-latest.jar:git-Spigot-2086bb0-d0a3620]
	at net.KeterDev.ChatMath.SolveTheExpression.onAnswer(SolveTheExpression.java:109) [ChatMath-Challenge-1.0-SNAPSHOT.jar:?]
	at net.KeterDev.ChatChallenge.EventsListener.onPlayerChats(EventsListener.java:44) [ChatChallenge-0.3-beta.jar:?]
	at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?]
	at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:?]
	at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:?]
	at java.lang.reflect.Method.invoke(Unknown Source) ~[?:?]
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:302) [spigot-latest.jar:git-Spigot-2086bb0-d0a3620]
	at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) [spigot-latest.jar:git-Spigot-2086bb0-d0a3620]
	at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:500) [spigot-latest.jar:git-Spigot-2086bb0-d0a3620]
	at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:482) [spigot-latest.jar:git-Spigot-2086bb0-d0a3620]
	at net.minecraft.server.v1_12_R1.PlayerConnection.chat(PlayerConnection.java:1319) [spigot-latest.jar:git-Spigot-2086bb0-d0a3620]
	at net.minecraft.server.v1_12_R1.PlayerConnection.a(PlayerConnection.java:1257) [spigot-latest.jar:git-Spigot-2086bb0-d0a3620]
	at net.minecraft.server.v1_12_R1.PacketPlayInChat$1.run(PacketPlayInChat.java:39) [spigot-latest.jar:git-Spigot-2086bb0-d0a3620]
	at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:?]
	at java.util.concurrent.FutureTask.run(Unknown Source) [?:?]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [?:?]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [?:?]
	at java.lang.Thread.run(Unknown Source) [?:?]