Dont know why this crash happened. I was just with a shulker box opened and moving torches across my hotbar.
Crash: https://paste.dimdev.org/bororesoqa.mccrash

MC 1.12.2, Forge 14.23.5.2768 (Latest RB) and Quark-r1.5-130

Also important to note i have installed Bauble Shulker Boxes (but this shulker wasnt on my bauble slot, and yes on the ground) and Advanced Shulker Boxes (like i said the shulker was opened from the ground and not from the inventory).

I don't think this is closed. I'm still experiencing this with r1.5-138, downloaded through the Twitch client. This crash started when I had r1.5-137 installed. After the first crash, I thought my game client was just running too long, so, thanks to the mandatory restart it deemed necessary, I reloaded and ran into the same crash. I also noticed that I had no shulker lids in my inventory (I should have had 5 left). I touched the lid, and then crashed again. I then upgraded to 138, and retried loading twice. The first time, I cheated in a shulker lid, touched it, and crashed, then, reloaded touched something else in my inventory, and again crashed.

What happened was I too went to the end, got 7 shulker lids, I then came back to my base. I initially was able to create a shulker box, but I think I shift-clicked them into my crafting grid without ever touching the lids, made the shulker box, put the shulker box into my ProjectE EMC tablet, and then went to put the shulker lid into the tablet, but got a "shutting down internal server" then crash to desktop just by touching the lid on my hot bar.

What I did to 'fix' my game was disable Qark, reload the game, then I was able to get into the game and do some inventory management. Unfortunately, it removed the Tinkers sword from my inventory I touched during the crash testing. Fortunately, it was pretty basic with limited XP on it, so no huge deal (This is just a game, so, never a huge deal or disappointment).

report.txt

After posting this, I re-enabled Quark and then again could not manage any inventory without a crash.

Investigating more, seems to be a more serious issue, i cant remove anything from inventories too (i equiped a pumpkin on my head, when i tried to remove it: https://paste.dimdev.org/ubojipuxel.mccrash

Strangely it only happened on my last save the previous one (same forge, quark, autoreglib versions) didnt have these issues.

I think i can provide the steps to make this crash:

• Create the world;
• Give yourself a shulker box with a loottable in its nbt (/give @s minecraft:white_shulker_box 1 0 {BlockEntityTag:{LootTable:"minecraft:chests/spawn_bonus_chest"}});
• Try to place it on the ground (without shifting). This will trigger this bug and the shulker box will return to the inventory without seeming to generate the loot;
• Now shift-place the shulker on the ground. It will properly place the box and you can open that.
• When you try to pick any of the items the game will crash, when you return to the world the picked item will be on the ground. Trying to interact with (place in the armour if possible) will just crash the game afterwards.

I am experiencing the same issue.

If it helps, here is my crash report. Follow the same process as Vpontin to recreate crash.
https://pastebin.com/veZekGkD