Fix #4216

[mcchampions]

Description

Fix #4216

Proposed changes

Make the value of tickingLocations thread-safe

new HashSet() -> Collections.newSetFromMap(new ConcurrentHashMap<>())

Initialize a new HashSet on read time to avoid exceptions

Related Issues (if applicable)

4216

Checklist

• [ ] I have fully tested the proposed changes and promise that they will not break everything into chaos.
• [ ] I have also tested the proposed changes in combination with various popular addons and can confirm my changes do not break them.
• [x] I have made sure that the proposed changes do not break compatibility across the supported Minecraft versions (1.16. - 1.20.).
• [x] I followed the existing code standards and didn't mess up the formatting.
• [ ] I did my best to add documentation to any public classes or methods I added.
• [ ] I have added Nonnull and Nullable annotations to my methods to indicate their behaviour for null values
• [ ] I added sufficient Unit Tests to cover my code.

[github-actions[bot]]

Your Pull Request was automatically labelled as: "✨ Fix" Thank you for contributing to this project! ❤️

[github-actions[bot]]

Slimefun preview build

A Slimefun preview build is available for testing! Commit: 4ffef583

https://preview-builds.walshy.dev/download/Slimefun/4218/4ffef583

Note: This is not a supported build and is only here for the purposes of testing. Do not run this on a live server and do not report bugs anywhere but this PR!