Sliper Lena

I'm using Minecraft 1.7.9

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)

I tried to create a custom green villager I open the interact interface and it crashed 😞