If the game autosaves while on a ladder and you load that save, it will cause you to instantly start falling.
I noticed this after being softlocked due to the Rozital scouts bug, so I had no other save to resort to.
Viewing post in Voices of the Void 0.8.2 Bug Reports
You can turn off physics damage in experimental settings before you load in to stop the fall from killing you. Alternatively, if you have a number pad on your keyboard, numpad . is debug teleport and will transport you safely to the ground. If you don't have a number pad, like me, you can also set it in keybinds to another key.