Thanks for taking the time to open a bug report!

Describe the bug
When i join the server it flood me with errors of unable to give skull object because of the latest SkinRestorer version

To Reproduce
Steps to reproduce the behavior:

1. Server is offline mode
2. Get latest skin restorer
3. Give your self skull item with skull owner's skin
4. Get the error

Expected behavior
For the plugin to not spam errors and maybe be compatible

Screenshots

Pastebin
It should be detailed enough from the above

Please complete the following information:
Paper 1.8.8
Java 11
ItemJoin v5.2.5

Additional context
Nope

Duplicate of #515 please see that issue for the resolution, (the latest snapshot).