stackmobs stacktrace

21.05 22:37:19 [Server] ERROR Could not pass event EntityDeathEvent to StackMob v1.8.1
21.05 22:37:19 [Server] INFO org.bukkit.event.EventException: null
21.05 22:37:19 [Server] INFO at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) ~[Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:499) [Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:484) [Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at org.bukkit.craftbukkit.v1_12_R1.event.CraftEventFactory.callEntityDeathEvent(CraftEventFactory.java:394) [Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at net.minecraft.server.v1_12_R1.EntityLiving.die(EntityLiving.java:1108) [Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at net.minecraft.server.v1_12_R1.EntityZombie.die(EntityZombie.java:429) [Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at net.minecraft.server.v1_12_R1.EntityLiving.damageEntity(EntityLiving.java:950) [Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at net.minecraft.server.v1_12_R1.EntityMonster.damageEntity(EntityMonster.java:44) [Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at net.minecraft.server.v1_12_R1.EntityZombie.damageEntity(EntityZombie.java:163) [Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at net.minecraft.server.v1_12_R1.EntityHuman.attack(EntityHuman.java:999) [Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at net.minecraft.server.v1_12_R1.EntityPlayer.attack(EntityPlayer.java:1292) [Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at net.minecraft.server.v1_12_R1.PlayerConnection.a(PlayerConnection.java:1602) [Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at net.minecraft.server.v1_12_R1.PacketPlayInUseEntity.a(SourceFile:69) [Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at net.minecraft.server.v1_12_R1.PacketPlayInUseEntity.a(SourceFile:13) [Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at net.minecraft.server.v1_12_R1.PlayerConnectionUtils$1.run(SourceFile:13) [Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_131]
21.05 22:37:19 [Server] INFO at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_131]
21.05 22:37:19 [Server] INFO at net.minecraft.server.v1_12_R1.SystemUtils.a(SourceFile:46) [Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at net.minecraft.server.v1_12_R1.MinecraftServer.D(MinecraftServer.java:747) [Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at net.minecraft.server.v1_12_R1.DedicatedServer.D(DedicatedServer.java:405) [Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at net.minecraft.server.v1_12_R1.MinecraftServer.C(MinecraftServer.java:678) [Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:576) [Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at java.lang.Thread.run(Thread.java:748) [?:1.8.0_131]
21.05 22:37:19 [Server] INFO Caused by: java.lang.UnsupportedOperationException: Not supported.
21.05 22:37:19 [Server] INFO at org.bukkit.craftbukkit.v1_12_R1.entity.CraftZombie.setVillagerProfession(CraftZombie.java:50) ~[Spigot.jar:git-Spigot-6629162-c7920f4]
21.05 22:37:19 [Server] INFO at uk.antiperson.stackmob.utils.EntityUtils.createEntity(EntityUtils.java:106) ~[?:?]
21.05 22:37:19 [Server] INFO at uk.antiperson.stackmob.events.entity.DeathEvent.onDeath(DeathEvent.java:125) ~[?:?]