Main End Island may not generate in the middle

Summary:
Main End Island may not generate in the center (generated in circle shape). Because of this, the portal generates at 0 height and is clipped. Such a generation is probably very rare.

Steps to reproduce:

1. Create a world with seed 7339274973115517046.
2. Turn on cheats.
3. Enter the command: /setblock ~ ~ ~ end_portal.
4.  Go to the center of the island.

Observed results:
The island didn't generate in the center, causing the portal to generate at 0 height.

Expected results:
An island should be generated in the center.

Screenshots: