Fixes "invalid book tag" issue.

[SavageAvocado]

Information

This PR fixes https://github.com/EssentialsX/Essentials/issues/4912.

Details

Proposed fix: Fixes "invalid book tag" issue by setting a default author & title for written books.

Environments tested:

OS: Windows 10

Java version: 17.0.1

• [X] Most recent Paper version (1.18.2)
• [ ] CraftBukkit/Spigot/Paper 1.12.2
• [ ] CraftBukkit 1.8.8

Demonstration:

Before (Tested with EssentialsX 2.20.0) https://youtu.be/D7pgr_nSkAI

After (Tested by using the compiled version with this commit) https://youtu.be/MS0klLUz2A0