Console Error when opening GUI

[LeStegii]

Describe the bug, provide any errors Whenever I open a teleporter GUI on my server (Spigot 1.12.2) when playing with 1.7.10, I get this error in console. It works still fine and I can use the GUI, but the error is annoying. It seems like the error gets printed once for every item displayed.

Error https://hatebin.com/tfzwkyyive

How can we reproduce it? Steps to reproduce the behavior:

1. Login on 1.7.10
2. Open a custom brewing stand GUI
3. See the error.

Expected behaviour No error should be displayed

Screenshots GUI

ViaVersion Dump: Dump: https://dump.viaversion.com/f2bddb06d7322d03b5aacaf215d77e1e2040bceedf285cd053c2c45932b05b23

Additional server info I'm using Travertine

Checklist (mark with [X] to check)

• [x] I have included a ViaVersion dump
• [x] If applicable, I have included a paste (not a screenshot) of the error
• [x] I have tried a build from https://ci.viaversion.com/ and the issue still persists
• [x] I have looked at https://www.spigotmc.org/resources/viarewind-legacy-support.52924/ and it does not offer a fix for my problem

[FlorianMichael]

Looks like the error url doesn't work anymore, if the issue still appears, open a new ticket here on GitHub.