So, as i was busy using a hired miner to... mine... i approached them, then crashed and i was given this crash log.

---- Minecraft Crash Report ----
// There are four lights!

Time: 7/23/14 10:55 PM
Description: Ticking entity

java.lang.ArrayIndexOutOfBoundsException: 3
at mca.chore.ChoreMining.doHarvestBlock(ChoreMining.java:575)
at mca.chore.ChoreMining.runActiveAI(ChoreMining.java:425)
at mca.chore.ChoreMining.runChoreAI(ChoreMining.java:171)
at mca.entity.AbstractEntity.updateChores(AbstractEntity.java:2795)
at mca.entity.AbstractEntity.func_70071_h_(AbstractEntity.java:286)
at mca.entity.EntityVillagerAdult.func_70071_h_(EntityVillagerAdult.java:278)
at net.minecraft.world.World.func_72866_a(World.java:2350)
at net.minecraft.world.WorldServer.func_72866_a(WorldServer.java:719)
at net.minecraft.world.World.func_72870_g(World.java:2311)
at net.minecraft.world.World.func_72939_s(World.java:2157)
at net.minecraft.world.WorldServer.func_72939_s(WorldServer.java:550)
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:668)
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:587)
at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:129)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:484)
at net.minecraft.server.ThreadMinecraftServer.run(SourceFile:583)

If more of the log is required, it would be much appreciated.

May no longer be relevant in 1.7.2 and update. If it occurs on 1.7.2 post again.