When you are in creative flight mode (not necessarily creative mode) and open a gui while near a ladder you start to go down it.

This part of the code should probably check if the player is in flight mode, i do not know the exact method otherwise i would have created a pull request instead:

My usecase: we have a mineshaft ladder right next to our storage system (pretty pipes gui block just to the right), as well as levels in the shaft (with mostly bee stuff) on either side, we recently unlocked ars noveau creative flight in enigmatica 6 so we tend to fly up and down in the same shaft as the ladder whilst opening guis a lot, promptly causing us to descend all the time:

(removing the ladder or flying in the ladderless column would be an option, both both are impractical and get in the way)