Yeah i'm having the same issue. Seems like certain images either didn't extract properly or at all. Whole backgrounds for certain areas (like the forest at night) are not in the folder after using the DXEtract program. I tried re extracting and it didn't work. If anyone else has suggestions or an answer to this issue it would be appreciated. (or probably just a data folder upload)
Dude, I found a solution for the missing picture ("/Picture/black_sasi.png").
-Solution-
1.In the game folder, copy the ("/Data/Picture/black.png") file from there and paste in the same folder.
2 Rename the copied file ("black_sasi.png") (The name of the missing file) .
3.Profit, my friend

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(My solution assumes you used DXExtract to get the Data folder from Data.wolf for the translation files, if not, well, Just DO IT xDD)
-SolutionEnd-
This fix will make the game stop throwing that error during the scene, practicly solving the issue. From what I tested, that .png probably was a filter (try getting the same scene in the japanese version) or something, so replacing said picture with the black.png will only add a transparent black picture which can be easily ignored. So far that was the only problem I have found, if you guys find more errors, please tell, though I'd figure an easy solution to the problem would be replacing the missing files with similar files (with the same extension), granted it's not something important (ex. an enemy sprite), but from the looks of it, the important files were extracted properly (by using DXExtract, which extracts more files than Arc_converter).
May you keep enjoying the game as much as I do

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(Also, if you guys agree with my solution, it should probably be added at the top of the thread, it's pretty essential for escaping the dark clutches of the sinister Error lord

) )