crashing on clicking on a vehicle, where a player is inside

[fredi-python]

My server is crashing, by doing right click on a vehicle (only if there is somebody in there)

ServerError: AsyncErr: Lua: Runtime error from mod 'vehicles' in callback luaentity_run_simple_callback(): /home/debian/minetest/bin/../mods/vehicles/init.lua:524: bad argument #2 to 'set_attach' (string expected, got userdata)