WORLDEDIT-2605 - Reported by joshp102

this is what the console says when it happens

15.01 13:05:45 [Server] SEVERE at net.minecraft.server.v1_4_6.ThreadServerApplication.run(SourceFile:849)
15.01 13:05:45 [Server] SEVERE at net.minecraft.server.v1_4_6.MinecraftServer.run(MinecraftServer.java:427)
15.01 13:05:45 [Server] SEVERE at net.minecraft.server.v1_4_6.MinecraftServer.q(MinecraftServer.java:494)
15.01 13:05:45 [Server] SEVERE at net.minecraft.server.v1_4_6.DedicatedServer.r(DedicatedServer.java:224)
15.01 13:05:45 [Server] SEVERE at net.minecraft.server.v1_4_6.MinecraftServer.r(MinecraftServer.java:598)
15.01 13:05:45 [Server] SEVERE at net.minecraft.server.v1_4_6.DedicatedServerConnection.b(SourceFile:30)
15.01 13:05:45 [Server] SEVERE at net.minecraft.server.v1_4_6.ServerConnection.b(SourceFile:39)
15.01 13:05:45 [Server] SEVERE at net.minecraft.server.v1_4_6.PlayerConnection.d(PlayerConnection.java:112)
15.01 13:05:45 [Server] SEVERE at net.minecraft.server.v1_4_6.NetworkManager.b(NetworkManager.java:290)
15.01 13:05:45 [Server] SEVERE at net.minecraft.server.v1_4_6.Packet3Chat.handle(Packet3Chat.java:44)
15.01 13:05:45 [Server] SEVERE at net.minecraft.server.v1_4_6.PlayerConnection.a(PlayerConnection.java:853)
15.01 13:05:45 [Server] SEVERE at net.minecraft.server.v1_4_6.PlayerConnection.chat(PlayerConnection.java:898)
15.01 13:05:45 [Server] SEVERE at net.minecraft.server.v1_4_6.PlayerConnection.handleCommand(PlayerConnection.java:980)
15.01 13:05:45 [Server] SEVERE at org.bukkit.craftbukkit.v1_4_6.CraftServer.dispatchCommand(CraftServer.java:510)
15.01 13:05:45 [Server] SEVERE at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:186)
15.01 13:05:45 [Server] SEVERE at com.sk89q.bukkit.util.DynamicPluginCommand.execute(DynamicPluginCommand.java:52)
15.01 13:05:45 [Server] SEVERE at com.sk89q.worldedit.bukkit.WorldEditPlugin.onCommand(WorldEditPlugin.java:197)
15.01 13:05:45 [Server] SEVERE at com.sk89q.worldedit.WorldEdit.handleCommand(WorldEdit.java:1339)
15.01 13:05:45 [Server] SEVERE at com.sk89q.minecraft.util.commands.CommandsManager.execute(CommandsManager.java:425)
15.01 13:05:45 [Server] SEVERE at com.sk89q.minecraft.util.commands.CommandsManager.executeMethod(CommandsManager.java:509)
15.01 13:05:45 [Server] SEVERE at com.sk89q.worldedit.WorldEdit$1.invokeMethod(WorldEdit.java:172)
15.01 13:05:45 [Server] SEVERE at com.sk89q.worldedit.WorldEdit$1.invokeMethod(WorldEdit.java:241)
15.01 13:05:45 [Server] SEVERE at com.sk89q.minecraft.util.commands.CommandsManager.invokeMethod(CommandsManager.java:522)
15.01 13:05:45 [Server] SEVERE at java.lang.reflect.Method.invoke(Unknown Source)
15.01 13:05:45 [Server] SEVERE at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
15.01 13:05:45 [Server] SEVERE at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
15.01 13:05:45 [Server] SEVERE at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
15.01 13:05:45 [Server] SEVERE at com.sk89q.worldedit.commands.RegionCommands.set(RegionCommands.java:74)
15.01 13:05:45 [Server] SEVERE at com.sk89q.worldedit.WorldEdit.getBlockPattern(WorldEdit.java:608)
15.01 13:05:45 [Server] SEVERE at com.sk89q.worldedit.WorldEdit.getBlock(WorldEdit.java:549)
15.01 13:05:45 [Server] SEVERE at com.sk89q.worldedit.WorldEdit.getBlock(WorldEdit.java:355)
15.01 13:05:45 [Server] SEVERE at com.sk89q.worldedit.WorldEdit.getBlock(WorldEdit.java:414)
15.01 13:05:45 [Server] SEVERE at com.sk89q.worldedit.bukkit.BukkitWorld.isValidBlockType(BukkitWorld.java:872)
15.01 13:05:45 [Server] SEVERE java.lang.NoClassDefFoundError: net/minecraft/server/Block