Fix another bug with interaction fix and add more interaction tests

[WalshyDev]

Description

Not all blocks will have an inventory, we missed a null check.
MockBukkit didn't catch as we can't check for viewers today :/

Proposed changes

• Adds a null check to inventory closing in block break.
• Adds basic item interaction and basic block interaction tests

Related Issues (if applicable)

https://pastebin.com/UiCbddCm

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.
• I have made sure that the proposed changes do not break compatibility across the supported Minecraft versions (1.16.* - 1.20.*).
• 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]

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

[github-actions]

Slimefun preview build

A Slimefun preview build is available for testing!
Commit: 4d0f6712

https://preview-builds.walshy.dev/download/Slimefun/4090/4d0f6712

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!

[WalshyDev]

Tested a few items and blocks in game, all looks good this time around.

[J3fftw1]

Just incorrect docs

[sonarcloud]

Quality Gate passed

The SonarCloud Quality Gate passed, but some issues were introduced.

18 New issues
0 Security Hotspots
71.4% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud