19:58:49 [SEVERE] Unexpected exception
java.lang.IllegalArgumentException: Unknown entity
        at org.bukkit.craftbukkit.entity.CraftEntity.getEntity(CraftEntity.java:102)
        at net.minecraft.server.Entity.getBukkitEntity(Entity.java:1166)
        at net.minecraft.server.Entity.move(Entity.java:543)
        at net.minecraft.server.EntityExperienceOrb.s_(SourceFile:103)
        at net.minecraft.server.World.entityJoinedWorld(World.java:1192)
        at net.minecraft.server.WorldServer.entityJoinedWorld(WorldServer.java:48)
        at net.minecraft.server.World.playerJoinedWorld(World.java:1174)
        at net.minecraft.server.World.cleanUp(World.java:1089)
        at net.minecraft.server.MinecraftServer.h(MinecraftServer.java:460)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:374)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:417)