This occurred when a wife/husband/etc has died and you look at the ring on the ground, or the "mca:memorial". This error is reported by HWaila.
Please fix this! Simply logging in again crashes the game immediately.
Minecraft version: 1.12.2
Mod version: 5.3.1

Crash log section below, whole crash log is at the bottom.
[16:44:39] [main/FATAL] [net.minecraft.client.Minecraft]: Unreported exception thrown! java.lang.NullPointerException: mca:memorial from mod Minecraft Comes Alive returned a null ItemStack in getPickBlock(...). Please report this to them. at mcp.mobius.waila.api.impl.DataAccessorCommon.set(DataAccessorCommon.java:64) ~[DataAccessorCommon.class:?] at mcp.mobius.waila.api.impl.DataAccessorCommon.set(DataAccessorCommon.java:44) ~[DataAccessorCommon.class:?] at mcp.mobius.waila.overlay.WailaTickHandler.tickClient(WailaTickHandler.java:76) ~[WailaTickHandler.class:?] at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_209_WailaTickHandler_tickClient_ClientTickEvent.invoke(.dynamic) ~[?:?] at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90) ~[ASMEventHandler.class:?] at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:179) ~[EventBus.class:?] at net.minecraftforge.fml.common.FMLCommonHandler.onPreClientTick(FMLCommonHandler.java:343) ~[FMLCommonHandler.class:?] at net.minecraft.client.Minecraft.func_71407_l(Minecraft.java:1706) ~[bib.class:?] at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:1096) ~[bib.class:?] at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:397) [bib.class:?] at net.minecraft.client.main.Main.main(SourceFile:123) [Main.class:?] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_171] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_171] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_171] at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_171] at net.minecraft.launchwrapper.Launch.launch(Launch.java:135) [launchwrapper-1.12.jar:?] at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.12.jar:?]
crash-2018-05-22_16.33.13-client.txt

This is on purpose on Hwyla's part - apparently (for them) it is 'bad style'? Closing.

Almost 3 months from the open of this issue, any answer @cowpod ?

I didn't read the stacktrace. It seems it's a Hywla/Waila issue as they are not checking the property they are asking for to be null.

I mark my issue as solved as is Hwyla/Waila issue.