Error

org.bukkit.craftbukkit.scheduler.CraftWorker.run(CraftWorker.java:34)
19.06 17:46:08 [Server] INFO at com.dogonfire.gods.Gods$1.run(Gods.java:214)
19.06 17:46:08 [Server] INFO at com.dogonfire.gods.GodManager.update(GodManager.java:1533)
19.06 17:46:08 [Server] INFO at com.dogonfire.gods.GodManager.manageBelievers(GodManager.java:1366)
19.06 17:46:08 [Server] INFO at com.dogonfire.gods.GodManager.blessPlayerWithItem(GodManager.java:803)
19.06 17:46:08 [Server] INFO at com.dogonfire.gods.GodManager.giveItem(GodManager.java:711)
19.06 17:46:08 [Server] INFO at org.bukkit.craftbukkit.CraftWorld.dropItem(CraftWorld.java:304)
19.06 17:46:08 [Server] INFO at net.minecraft.server.World.addEntity(World.java:862)
19.06 17:46:08 [Server] INFO at net.minecraft.server.World.addEntity(World.java:892)
19.06 17:46:08 [Server] INFO at org.bukkit.craftbukkit.event.CraftEventFactory.callItemSpawnEvent(CraftEventFactory.java:252)
19.06 17:46:08 [Server] INFO at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:460)
19.06 17:46:08 [Server] INFO at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62)
19.06 17:46:08 [Server] INFO at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:302)
19.06 17:46:08 [Server] INFO at java.lang.reflect.Method.invoke(Method.java:601)
19.06 17:46:08 [Server] INFO at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
19.06 17:46:08 [Server] INFO at sun.reflect.GeneratedMethodAccessor137.invoke(Unknown Source)
19.06 17:46:08 [Server] INFO at org.bukkit.event.Listener.onItemSpawn(Listener:0)
19.06 17:46:08 [Server] INFO java.lang.IllegalAccessError: Synchronized code got accessed from another thread: com.dogonfire.gods.Gods$1