PreventPortalTraps - dniym/IllegalStack GitHub Wiki
ON BY DEFAULT - Affects ALL Versions
Sick of players getting stuck in nether portals and never being able to escape without admin help? IllegalStack will check for trapped portals when a player logs in, if there's no valid exit from the portal the portal will be broken allowing the player to mine their way out or teleport to /home or /spawn.
To enable / disable this protection use the following command: /istack toggle PreventPortalTraps