Villager trading bug

Minecraft Crash Report ----
// This is a token for 1 free hug. Redeem at your nearest Mojangsta: @unknown

Time: 14.4.24 18.25
Description: Ticking memory connection

java.lang.NullPointerException: Ticking memory connection
at afk.a(SourceFile:55)
at xs.a(SourceFile:292)
at zr.a(SourceFile:58)
at yp.a(SourceFile:238)
at ng.a(SourceFile:623)
at iu.a(SourceFile:32)
at iu.a(SourceFile:10)
at eg.a(SourceFile:166)
at nb.c(SourceFile:134)
at net.minecraft.server.MinecraftServer.v(SourceFile:530)
at net.minecraft.server.MinecraftServer.u(SourceFile:443)
at btq.u(SourceFile:117)
at net.minecraft.server.MinecraftServer.run(SourceFile:359)
at lh.run(SourceFile:618)

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

– Head –
Stacktrace:
at afk.a(SourceFile:55)
at xs.a(SourceFile:292)
at zr.a(SourceFile:58)
at yp.a(SourceFile:238)
at ng.a(SourceFile:623)
at iu.a(SourceFile:32)
at iu.a(SourceFile:10)
at eg.a(SourceFile:166)

– Ticking connection –
Details:
Connection: eg@ae083a
Stacktrace:
at nb.c(SourceFile:134)
at net.minecraft.server.MinecraftServer.v(SourceFile:530)
at net.minecraft.server.MinecraftServer.u(SourceFile:443)
at btq.u(SourceFile:117)
at net.minecraft.server.MinecraftServer.run(SourceFile:359)
at lh.run(SourceFile:618)

– System Details –
Details:
Minecraft Version: 1.7.5
Operating System: Windows XP (x86) version 5.1
Java Version: 1.7.0_55, Oracle Corporation
Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
Memory: 47449328 bytes (45 MB) / 184496128 bytes (175 MB) up to 518979584 bytes (494 MB)
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Profiler Position: N/A (disabled)
Vec3 Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
Player Count: 1 / 8; [mv['aidasjonikas'/61, l='Blocks vs. Zombies by SethBling', x=999,87, y=64,00, z=-6,87]]
Type: Integrated Server (map_client.txt)
Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.