First crash report I'll ever write but I'll attempt to add in as much information as possible
Apparently I cannot attach a textfile containing the full crashlog, and I cannot use inline codeblocks either? Might need some assistance with that.

-- Head --
Stacktrace:
at net.minecraft.world.World.func_82733_a(World.java:3218)
at net.minecraft.world.World.func_72872_a(World.java:3213)
at riskyken.armourersWorkshop.common.handler.DollCraftinghandler.onMinecartUpdateEvent(DollCraftinghandler.java:27)
at cpw.mods.fml.common.eventhandler.ASMEventHandler_894_DollCraftinghandler_onMinecartUpdateEvent_MinecartUpdateEvent.invoke(.dynamic)
at cpw.mods.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:54)
at cpw.mods.fml.common.eventhandler.EventBus.post(EventBus.java:138)
at net.minecraft.entity.item.EntityMinecart.func_70071_h_(EntityMinecart.java:407)
at net.minecraft.world.World.func_72866_a(World.java:2070)
at net.minecraft.world.WorldServer.func_72866_a(WorldServer.java:648)
at net.minecraft.world.World.func_72870_g(World.java:2034)

-- Entity being ticked --
Details:
Entity Type: MinecartChest (mods.railcraft.common.carts.EntityCartChest)
Entity ID: 5769
Entity Name: Minecart with Chest
Entity's Exact location: -334,50, 38,50, 382,50
Entity's Block location: World: (-335,38,382), Chunk: (at 1,2,14 in -21,23; contains blocks -336,0,368 to -321,255,383), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
Entity's Momentum: 0,00, -0,00, 0,00
Stacktrace:
at net.minecraft.world.World.func_72939_s(World.java:1887)
at net.minecraft.world.WorldServer.func_72939_s(WorldServer.java:489)

-- Affected level --
Details:
Level name: Bordworld
All players: 1 total; [EntityPlayerMP['DoomsdayBistian'/5742, l='Bordworld', x=-208,44, y=64,00, z=306,19]]
Chunk stats: ServerChunkCache: 1014 Drop: 0
Level seed: -8326269835958595845
Level generator: ID 00 - default, ver 1. Features enabled: true
Level generator options:
Level spawn location: World: (-23,64,-58), Chunk: (at 9,4,6 in -2,-4; contains blocks -32,0,-64 to -17,255,-49), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
Level time: 1241232 game time, 1335812 day time
Level dimension: 0
Level storage version: 0x04ABD - Anvil
Level weather: Rain time: 18065 (now: false), thunder time: 31686 (now: false)
Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: true
Stacktrace:
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:636)
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:547)
at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:111)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:427)
at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:685)

Looks like the mod crashes whenever the doll crafting handler fires on a railcraft-overridden minecart? Haven't isolated the mods yet, so I don't even know what that handler is supposed to do or if Railcraft is causing it but I'm taking a shot in the dark.

For reference, I'm running Railcraft 9.4.0.0 and Armourers Workshop 0.22.2.37 and I get the crash on both, Forge 10.13.2.1263 and .1230. Tell me if you need the full modlist.

I'd assume that the error occurs in line 27 in common/handler/DollCraftinghandler.java

entities = world.getEntitiesWithinAABB(EntityItem.class, event.minecart.getCollisionBox(event.minecart));

Can't possibly mean that event.minecart is null, but getCollisionBox(event.minecart) might return null? Don't have a setup mcp enviroment around so I can't check. Might be a messup on Railcraft's side?

It's best to use pastebin for things like crash logs.

Can confirm that it doesn't play nice with Railcraft and works otherwise.

Full crashlog for isolated instance: http://pastebin.com/9TF6ycpH

Should be fixed. :) http://jenkins.rx14.co.uk/job/RiskyKen/job/Armourers-Workshop/41/

Works like a charm