Amethyst geodes can generate in a stronghold and can potentially destroy the end portal frames

The bug

Amethyst geodes are able to generate in a stronghold. As shown in the screenshot, half of the geode has generated without containing any calcite or smooth basalt blocks. It may also generate in the end portal room in some seeds, potentially destroying one of the frames of the end portal.

How to reproduce

Caves & Cliffs 21w20a Preview Datapack 
Seed: 5872862164234670138
Coordinates: /execute in minecraft:overworld run tp @s -18.17 -34.82 1557.92 477.28 23.25