Fixed altoclef crashing if quitting the world while the task is running.

[MarvionKirito]

Summary

Fixed altoclef crashing if quitting the world while the task is running.

Information

• [x] This PR fixes an issue.
• [ ] This PR adds something new (e.g. new method or parameters).
• [ ] This PR is a breaking change (e.g. methods or parameters removed/renamed).
• [ ] This PR is not a code change (e.g. documentation, README, examples, ...).

Checklist

• [x] I have searched the open pull requests for duplicates.
• [x] If code changes were made then they have been tested.