Bug: NullPointerException in LegalMovementManager during player movement detection

### What happened?

The List maintained by Lambda mod's LegalMovementManager contains null elements. When the game tries to invoke .priority() or .applyPreTickModify() on a null MovementModifier, it throws a NullPointerException and crashes the game.

### What should have happened?

The game should have loaded

### Version

0.10

### Log Output

_No response_