Game crashes when trying to load world list

What I expected to happen was...:

Singleplayer worlds should have loaded

What actually happened was...:
The game crashed

Steps to Reproduce:
1. Click on "Singleplayer" in Main Menu
2. Wait
3. Game Crashes

Crash Report:
The game crashed whilst couldn't load level list
Error: java.lang.NullPointerException: Cannot invoke "java.lang.Comparable.compareTo(Object)" because "pivot" is null
Exit Code: -1
This did not occur in Snapshot 22w15a