Bukkit

What steps will reproduce the problem?
1. Unsure
2.
3.

What is the expected output? What do you see instead?

Happens automatically without anyone needing to be on the server.

What version of the product are you using?

Latest: 1.2.1

Do you have an error log of what happened?

2013-09-16 02:37:21 [SEVERE] Exception in thread "Timer-0"
2013-09-16 02:37:21 [SEVERE] java.lang.IllegalStateException: Asynchronous entity world add!
2013-09-16 02:37:21 [SEVERE]     at net.minecraft.server.v1_6_R2.World.a(World.java:2516)
2013-09-16 02:37:21 [SEVERE]     at net.minecraft.server.v1_6_R2.Chunk.addEntities(Chunk.java:697)
2013-09-16 02:37:21 [SEVERE]     at net.minecraft.server.v1_6_R2.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:128)
2013-09-16 02:37:21 [SEVERE]     at net.minecraft.server.v1_6_R2.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:84)
2013-09-16 02:37:21 [SEVERE]     at org.bukkit.craftbukkit.v1_6_R2.CraftWorld.getChunkAt(CraftWorld.java:118)
2013-09-16 02:37:21 [SEVERE]     at org.bukkit.craftbukkit.v1_6_R2.CraftWorld.getBlockAt(CraftWorld.java:82)
2013-09-16 02:37:21 [SEVERE]     at de.eitorfVerci_.sharemarket.Schild.Sign_Methoden.getSignAtLoc(Sign_Methoden.java:143)
2013-09-16 02:37:21 [SEVERE]     at de.eitorfVerci_.sharemarket.Schild.Sign.Sign_View.update(Sign_View.java:162)
2013-09-16 02:37:21 [SEVERE]     at de.eitorfVerci_.sharemarket.Schild.Sign_Methoden.updateSign(Sign_Methoden.java:79)
2013-09-16 02:37:21 [SEVERE]     at de.eitorfVerci_.sharemarket.Daten.LokaleDaten.setShareId(LokaleDaten.java:34)
2013-09-16 02:37:21 [SEVERE]     at de.eitorfVerci_.sharemarket.Rechnungen.Trend.setTrend(Trend.java:20)
2013-09-16 02:37:21 [SEVERE]     at de.eitorfVerci_.sharemarket.Rechnungen.Trend.execute(Trend.java:224)
2013-09-16 02:37:21 [SEVERE]     at de.eitorfVerci_.sharemarket.Schedule.Schedule_Verlauf.run(Schedule_Verlauf.java:33)
2013-09-16 02:37:21 [SEVERE]     at java.util.TimerThread.mainLoop(Timer.java:555)
2013-09-16 02:37:21 [SEVERE]     at java.util.TimerThread.run(Timer.java:505)

Please provide any additional information below.

did you have the problem more than once ?