'characters/diane/layeredimage/diane_body_b_hay_feeding_nightgown1.png' is a file, that is missing in folder 'characters/diane/layeredimage'. You have that folder, otherwise not much would be working at all for diane. It's packed inside the .rpa files.
However, this bug is not so simple. They messed up the daytime, default image and Diane state machine. Depending on time of day and the configured outfit, the game constructs file names to look for. It should simply not happen that Diane is in a state that she wears the nightgown in the barn, therefore it is not the missing file but the wrong state.
I tried to clean that up a bit in my mod. You may want to see if it is fixing it for you. If the error is still there, attach a safegame here and I will see if I can fix it.