Mangrove trees can generate on stone

Summary:
Mangrove trees can generate on stone (/deepslate). The generation of such trees happened in an open cave.

Seed: -5721758910070358785
Coords: 454 13 729

Steps to reproduce:

1. Create a world with the specified seed.
2. Visit the specified coordinates.

Observed results:
Mangrove trees generated on stone (/deepslate).

Expected results:
Mangrove trees cannot generate on stone (/deepslate).

Screenshots: