I just made a custom villager and I tryed to trade with him but unfortunally the game crashed

Windows 7 64bit 4 core i7 - AMD Radeon HD 7770 - 8GB ram
Java 64 bit

---- Minecraft Crash Report ----
// Don't be sad, have a hug! <3

Time: 24.10.13 12:47
Description: Ticking memory connection

java.lang.NullPointerException: Ticking memory connection
at aey.a(SourceFile:55)
at xg.a(SourceFile:292)
at zf.a(SourceFile:58)
at yd.a(SourceFile:238)
at mw.a(SourceFile:623)
at ik.a(SourceFile:32)
at ik.a(SourceFile:10)
at ef.a(SourceFile:143)
at mr.c(SourceFile:134)
at net.minecraft.server.MinecraftServer.u(SourceFile:529)
at net.minecraft.server.MinecraftServer.t(SourceFile:441)
at bsi.t(SourceFile:117)
at net.minecraft.server.MinecraftServer.run(SourceFile:358)
at kx.run(SourceFile:617)

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

– Head –
Stacktrace:
at aey.a(SourceFile:55)
at xg.a(SourceFile:292)
at zf.a(SourceFile:58)
at yd.a(SourceFile:238)
at mw.a(SourceFile:623)
at ik.a(SourceFile:32)
at ik.a(SourceFile:10)
at ef.a(SourceFile:143)

– Ticking connection –
Details:
Connection: ef@17fb7f8c
Stacktrace:
at mr.c(SourceFile:134)
at net.minecraft.server.MinecraftServer.u(SourceFile:529)
at net.minecraft.server.MinecraftServer.t(SourceFile:441)
at bsi.t(SourceFile:117)
at net.minecraft.server.MinecraftServer.run(SourceFile:358)
at kx.run(SourceFile:617)

– System Details –
Details:
Minecraft Version: 1.7.1
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.7.0_40, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 231203008 bytes (220 MB) / 385351680 bytes (367 MB) up to 2863661056 bytes (2731 MB)
JVM Flags: 1 total; -Xmx3G
AABB Pool Size: 101 (5656 bytes; 0 MB) allocated, 69 (3864 bytes; 0 MB) used
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Profiler Position: N/A (disabled)
Vec3 Pool Size: 12 (672 bytes; 0 MB) allocated, 4 (224 bytes; 0 MB) used
Player Count: 1 / 8; [ml['Gersin'/11, l='Mellon Killer', x=48.61, y=56.00, z=887.50]]
Type: Integrated Server (map_client.txt)
Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.