Spigot AntiXray async error

22:10:39 [WARNING] A task raised an exception.
net.minecraft.server.v1_6_R2.ReportedException: Exception getting block type in world
        at net.minecraft.server.v1_6_R2.World.getTypeId(World.java:243)
        at org.spigotmc.AntiXray.hasTransparentBlockAdjacent(AntiXray.java:195)
        at org.spigotmc.AntiXray.hasTransparentBlockAdjacent(AntiXray.java:195)
        at org.spigotmc.AntiXray.obfuscate(AntiXray.java:124)
        at net.minecraft.server.v1_6_R2.Packet56MapChunkBulk.compress(Packet56MapChunkBulk.java:94)
        at net.minecraft.server.v1_6_R2.Packet56MapChunkBulk.a(Packet56MapChunkBulk.java:175)
        at org.spigotmc.netty.PacketWriter.write(PacketWriter.java:62)
        at org.spigotmc.netty.NettyNetworkManager.queue0(NettyNetworkManager.java:197)
        at org.spigotmc.netty.NettyNetworkManager.access$000(NettyNetworkManager.java:33)
        at org.spigotmc.netty.NettyNetworkManager$3.run(NettyNetworkManager.java:182)
        at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:354)
        at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:366)
        at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:101)
        at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.IllegalStateException: Asynchronous entity world add!
        at net.minecraft.server.v1_6_R2.World.a(World.java:2493)
        at net.minecraft.server.v1_6_R2.Chunk.addEntities(Chunk.java:683)
        at net.minecraft.server.v1_6_R2.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:128)
        at net.minecraft.server.v1_6_R2.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:84)
        at net.minecraft.server.v1_6_R2.ChunkProviderServer.getOrCreateChunk(ChunkProviderServer.java:160)
        at net.minecraft.server.v1_6_R2.World.getChunkAt(World.java:310)
        at net.minecraft.server.v1_6_R2.World.getTypeId(World.java:235)
        ... 13 more