Hello, I am playing this game with many mods including Lex's Aircraft, but also many additions around Exotic Industries.

I have this error occuring : https://ibb.co/8rbZjRF

I have made a save game from which after loading it is easy to reproduce :

https://easyupload.io/2213o5

Load
select the red flying cargo ship
click the red button with a looping arrow to clear all waypoints
switch the vessel to automatic

For now i'm just going to avoid clicking the red button :) Maybe it is a compatibility problem with some of the other mods. I had some trouble making the save game because it felt like sometimes the error didn't occur when following previous step, it felt like a random luck that time i saved before testings and it occured. I'm still discovering the mod.

Also fixed now, thanks for reporting!