Minecraft Version: 1.12.2 forge-1.12.2-14.23.5.2808
Inventory Tweaks Version: InventoryTweaks-1.64-dev.jar

Not that I expect any resolution as I have already moved on but thought I should share in case it gives the author some insight. With the mods I have installed could just be a mod interaction as well.

Not sure what I did exactly. Big fingers, I sometimes hit keys I was no intending to.
Was focused on a golden lasso [extrautils2-1.12-1.9.9.jar] at the time.
The lasso disappeared, but here is the kicker so did two lassos that were in a iron backpack [IronBackpacks-1.12.2-3.0.8-12] at the time.

No crash, this was the message that was generated everything else was the usual minecraft logging.

To the author feel free to closethis after you have seen it like I said no idea what I did and could not even reproduce just wanted to share in case it was something that could help you out.

*****LOGGED CODE BELOW THIS *****

[16:22:16] [Client thread/ERROR] [inventorytweaks]: InvTweaks: [ERROR] [6] Failed to trigger shortcut: Inventory in invalid sate after move (l443 in HandlerShortcuts.java)
java.lang.RuntimeException: Inventory in invalid sate after move
at invtweaks.InvTweaksHandlerShortcuts.moveAll(InvTweaksHandlerShortcuts.java:443) ~[InvTweaksHandlerShortcuts.class:?]
at invtweaks.InvTweaksHandlerShortcuts.runShortcut(InvTweaksHandlerShortcuts.java:389) ~[InvTweaksHandlerShortcuts.class:?]
at invtweaks.InvTweaksHandlerShortcuts.handleShortcut(InvTweaksHandlerShortcuts.java:106) [InvTweaksHandlerShortcuts.class:?]
at invtweaks.InvTweaks.handleShortcuts(InvTweaks.java:966) [InvTweaks.class:?]
at invtweaks.InvTweaks.onTickInGUI(InvTweaks.java:246) [InvTweaks.class:?]
at invtweaks.forge.ClientProxy.onTick(ClientProxy.java:62) [ClientProxy.class:?]
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_1766_ClientProxy_onTick_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:182) [EventBus.class:?]
at net.minecraftforge.fml.common.FMLCommonHandler.onPreClientTick(FMLCommonHandler.java:344) [FMLCommonHandler.class:?]
at net.minecraft.client.Minecraft.func_71407_l(Minecraft.java:1708) [bib.class:?]
at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:1098) [bib.class:?]
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:398) [bib.class:?]
at net.minecraft.client.main.Main.main(SourceFile:123) [Main.class:?]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_201]
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_201]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_201]
at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_201]
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:?]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_201]
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_201]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_201]
at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_201]
at org.multimc.onesix.OneSixLauncher.launchWithMainClass(OneSixLauncher.java:196) [NewLaunch.jar:?]
at org.multimc.onesix.OneSixLauncher.launch(OneSixLauncher.java:231) [NewLaunch.jar:?]
at org.multimc.EntryPoint.listen(EntryPoint.java:143) [NewLaunch.jar:?]
at org.multimc.EntryPoint.main(EntryPoint.java:34) [NewLaunch.jar:?]
[16:22:16] [Client thread/INFO] [minecraft/GuiNewChat]: [CHAT] InvTweaks: [ERROR] [6] Failed to trigger shortcut: Inventory in invalid sate after move (l443 in HandlerShortcuts.java)