Version Info

• Minecraft, 1.12.2
• Packed Up, 1.1.0
• Core lib, ???

Steps to Reproduce
...
Launch modpack with updated backpack mod
crash

this didnt happen in previous update
Crash report (~/logs/latest.log)
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https://gist.github.com/Xplodin/89f12a0ee5b26e41a157765649390831

It seems the file did not get reobfuscated when I uploaded it. I have now reuploaded the file and simply downloading it again should fix the issue.
Thank you for reporting the issue!