NoLagg v1.89.0 generated an exception...

[Joelee7648]

Every so often I get this error:

2012-12-06 17:13:57 [WARNING] [NoLagg] Task #19 for NoLagg v1.89.0 generated an exception
java.lang.ClassCastException: net.minecraft.server.RegionFile cannot be cast to java.lang.ref.Reference
at com.bergerkiller.bukkit.nolagg.saving.RegionFileFlusher$1.run(RegionFileFlusher.java:30)
at org.bukkit.craftbukkit.scheduler.CraftTask.run(CraftTask.java:53)
at org.bukkit.craftbukkit.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:345)
at net.minecraft.server.MinecraftServer.r(MinecraftServer.java:529)
at net.minecraft.server.DedicatedServer.r(DedicatedServer.java:222)
at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:493)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:426)
at net.minecraft.server.ThreadServerApplication.run(SourceFile:856)

[Joelee7648]

Actually, I just noticed that it generates this exception at the regular back-up intervals of essentials