Mindcrack - Twilight Forest-related Crash

[INFO] nyaar[/127.0.0.1:57180] logged in with entity id 2639 at (303.67020540623236, 54.0, 343.327480823558)
2013-02-19 22:12:09 [INFO] Disconnecting nyaar [/127.0.0.1:57180]: Internal server error
2013-02-19 22:12:09 [WARNING] Failed to handle packet for nyaar [/127.0.0.1:57180]: t: Exception preparing structure feature
t: Exception preparing structure feature
	at im.c(ChunkProviderServer.java:140)
	at il.<init>(PlayerInstance.java:43)
	at ik.a(SourceFile:172)
	at ik.a(SourceFile:203)
	at gm.a(ServerConfigurationManager.java:163)
	at gm.c(ServerConfigurationManager.java:206)
	at gm.a(ServerConfigurationManager.java:123)
	at it.completeConnection(NetLoginHandler.java:198)
	at cpw.mods.fml.common.network.FMLNetworkHandler.handleClientConnection(FMLNetworkHandler.java:153)
	at cpw.mods.fml.common.network.FMLNetworkHandler.onConnectionReceivedFromClient(FMLNetworkHandler.java:107)
	at it.d(NetLoginHandler.java:182)
	at it.c(NetLoginHandler.java:75)
	at hu.a(ServerListenThread.java:56)
	at ht.b(SourceFile:29)
	at net.minecraft.server.MinecraftServer.r(MinecraftServer.java:703)
	at ho.r(DedicatedServer.java:269)
	at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:599)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:497)
	at fy.run(SourceFile:849)
Caused by: java.lang.IllegalArgumentException: n must be positive
	at java.util.Random.nextInt(Unknown Source)
	at twilightforest.structures.ComponentTFDarkTowerMain.a(ComponentTFDarkTowerMain.java:155)
	at twilightforest.structures.ComponentTFDarkTowerMainBridge.makeTowerWing(ComponentTFDarkTowerMainBridge.java:21)
	at twilightforest.structures.ComponentTFDarkTowerBridge.a(ComponentTFDarkTowerBridge.java:30)
	at twilightforest.structures.ComponentTFDarkTowerMain.makeNewLargeTower(ComponentTFDarkTowerMain.java:197)
	at twilightforest.structures.ComponentTFDarkTowerMain.a(ComponentTFDarkTowerMain.java:116)
	at twilightforest.structures.StructureTFMajorFeatureStart.<init>(StructureTFMajorFeatureStart.java:30)
	at twilightforest.world.MapGenTFMajorFeature.b(MapGenTFMajorFeature.java:22)
	at aev.a(SourceFile:33)
	at aaz.a(SourceFile:29)
	at twilightforest.world.ChunkProviderTwilightForest.d(ChunkProviderTwilightForest.java:379)
	at im.c(ChunkProviderServer.java:131)
	... 18 more