Sniffer tries to sniff out blocks outside the world border

The bug

Sniffer tries to sniff out the blocks outside the world border.

Reproduce steps

1. Create a Superflat world.

2. Use the following command:

   /worldborder set 6

   /worldborder set 6

3. Summon a sniffer.

4. Found it trying to sniff out the blocks outside the world border.