ENTITYDEATHEVENT CAUSE NOT TO DROP

[14:53:38 ERROR]: Could not pass event EntityDeathEvent to MythicMobs v4.9.1-SNAPSHOT-3267
java.lang.NullPointerException: null
        at io.lumine.xikage.mythicmobs.items.MythicItem.generateItemStack(MythicItem.java:437) ~[?:?]
        at io.lumine.xikage.mythicmobs.drops.droppables.MythicItemDrop.getDrop(MythicItemDrop.java:23) ~[?:?]
        at io.lumine.xikage.mythicmobs.adapters.bukkit.BukkitSkillTriggers.onDeathTrigger(BukkitSkillTriggers.java:421) ~[?:?]
        at com.destroystokyo.paper.event.executor.asm.generated.GeneratedEventExecutor1037.execute(Unknown Source) ~[?:?]
        at org.bukkit.plugin.EventExecutor.lambda$create$1(EventExecutor.java:69) ~[patched_1.15.2.jar:git-Paper-153]
        at co.aikar.timings.TimedEventExecutor.execute(TimedEventExecutor.java:80) ~[patched_1.15.2.jar:git-Paper-153]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:70) ~[patched_1.15.2.jar:git-Paper-153]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:607) ~[patched_1.15.2.jar:git-Paper-153]
        at org.bukkit.craftbukkit.v1_15_R1.event.CraftEventFactory.callEntityDeathEvent(CraftEventFactory.java:759) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.EntityLiving.d(EntityLiving.java:1380) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.EntityLiving.die(EntityLiving.java:1308) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.EntityLiving.damageEntity(EntityLiving.java:1152) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.EntityMonster.damageEntity(EntityMonster.java:52) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.EntityZombie.damageEntity(EntityZombie.java:318) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.EntityHuman.attack(EntityHuman.java:1113) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.EntityPlayer.attack(EntityPlayer.java:1705) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.PlayerConnection.a(PlayerConnection.java:2054) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.PacketPlayInUseEntity.a(PacketPlayInUseEntity.java:51) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.PacketPlayInUseEntity.a(PacketPlayInUseEntity.java:6) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.PlayerConnectionUtils.lambda$ensureMainThread$0(PlayerConnectionUtils.java:23) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.TickTask.run(SourceFile:18) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.IAsyncTaskHandler.executeTask(IAsyncTaskHandler.java:136) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.IAsyncTaskHandlerReentrant.executeTask(SourceFile:23) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.IAsyncTaskHandler.executeNext(IAsyncTaskHandler.java:109) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.MinecraftServer.ba(MinecraftServer.java:1038) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.MinecraftServer.executeNext(MinecraftServer.java:1031) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.IAsyncTaskHandler.awaitTasks(IAsyncTaskHandler.java:119) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.MinecraftServer.sleepForTick(MinecraftServer.java:1015) ~[patched_1.15.2.jar:git-Paper-153]
        at net.minecraft.server.v1_15_R1.MinecraftServer.run(MinecraftServer.java:938) ~[patched_1.15.2.jar:git-Paper-153]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_211]