What behaviour is observed:

ChangeSkin writes error on Paper 1.17.

What behaviour is expected:

ChangeSkin no writes error on Paper 1.17.

Steps/models to reproduce:

Use Changeskin on 1.17 Paper.

Plugin list:

Plugins (32): Admin-Chat, AuthMe, BetterGUI, ChangeSkin, ChatControlRed, Citizens, CompatNoCheatPlus, ConditionalCommands, CoreProtect, EasySetSpawn, FastLogin, HolographicDisplays, HolographicExtension, ImageMaps, ItemJoin, LPC, LuckPerms, MemoryViewer, Multiverse-Core, NashornPlus, NoCheatPlus, PinPrompt, PlaceholderAPI, PlugMan, ProtocolLib, StaffChat, TAB, Vault, WDLCompanion, WorldBorder, WorldEdit, WorldGuard

Environment description

Waterfall 1.17-R0.1-SNAPSHOT build 437, SQLite.

Plugin version:

ChangeSkin version 3.1-SNAPSHOT-1b4be18

Error Log:

https://pastebin.com/kqegWxxH

Configuration:

https://pastebin.com/BdjjK6nX

Is that the full error?

Sorry.
This is the full error:
https://pastebin.com/kqegWxxH

Should be fixed with 6cdccf7

New error on the new version:
https://pastebin.com/ZuzMVB9n

Thanks.