Describe the bug
Exactly as it says on the tin; opening a world where a backpack has an inception upgrade causes it to either crash, or remain frozen without rendering anything. This issue doesn't occur on the immediately previous versions of SB and Core. This issue happens regardless of if the upgrade is set to use the main or sub backpack inventories first, but doesn't happen if the upgrade is disabled.

Crash log: crash-2023-06-04_20.17.50-server.txt

To Reproduce
Steps to reproduce the behavior:

1. Get a backpack
2. Put an inception upgrade in the backpack.
3. Close the backpack.
4. Become unable to open the backpack again.
5. Attempt to drag the backpack to somewhere else in your inventory.
6. Crash.
7. Reopen the world.
8. Crash or freeze (I get crashes most often when not full screened, and vice versa for freezes).
9. Backport to sophisticatedbackpacks-1.19.2-3.18.47.836.jar and sophisticatedcore-1.19.2-0.5.57.275.jar
10. Reopen the world.
11. Don't crash or freeze.

Expected behavior
No crash/freeze when a backpack has the inception upgrade active.

Screenshots
I'll do you one better, here's a video of the crash setup: https://youtu.be/NN3MuiuuP3U

Versions
SB: sophisticatedbackpacks-1.19.2-3.18.50.847.jar
Core: sophisticatedcore-1.19.2-0.5.66.299.jar
Forge: 43.2.11

This is fixed in the latest release of sophisticated core. As for the lost backpacks there's unfortunately nothing i can do code wise, but you should still be able to retrieve them using /sbp list and /sbp give commands.

Another find after backporting again: it looks like the crash causes whichever backpack you clicked on in step 5 to get deleted; I'd originally had 7 backpacks total (1 main, 6 incepted) but in the video I only have 6 total, and after backporting again I'm down to 5.