Under unknown circumstances, assumed to be a player's first creation of a portal in a specific location?
The CAVE_AIR warnings print as follows;

This is odd as this is a default configuration, in a world without cave air, with no gate designs that include CAVE_AIR.

Environment:
Plugin Version: ALPHA-1.0.0.4 (Fresh Installation, Test Environment unit 3-Spigot-Online-MigNew-Modern-SQLite-Addons)
Server Version: 3491-Spigot-b081915-95d233 (MC: 1.18.2) Implementing API Version 1.18.2-R0.1-SNAPSHOT