Currently, the user can close an empty file and ST does not display a confirmation dialog, because the file is empty.
I think this logic is unsafe. If for example I have a temp file and I put important code inside, then for some reason I cut the code from it and paste it into another, non-temp file, then the temp file becomes empty.
If I then forget about it and close it, because I think it’s just an empty file, then I loose all the history of code editing in that file. An ST does not warn me, that that file, though empty, contained someting. That something could be easily restored by Undo.
I suggest to change the actual logic to: Close file without confirmation, only if the file was always empty, not only in the current state.