I got this error while playing, seems harmless as it doesn't crash anything, this copied from the error log:
[Picture display] File Read Error
Cannot find (Filepath)/Brave Alchemist Colette 1.03 JAST/Data/EVCG_e/e000/o000.png
Process mark:[MapEv 9 CommonEv 43 Live 72] A parallel process error means the pos is unknown
Just popped up on the screen for a while before I clicked it away and resumed the game.
I already unpacked EVCG_e to find the file, and it's just an empty/black .png file, which the OP mentioned.
Minor nuisance. Nothing gamebreaking.