i think the problem here is, that H&S and B&W require specific 1.30 patch files, that aren't available on the
gog downloaer page. as you can see, only the base game 1.30 patch is available there. this file applied to an installation with both expansions causes the error. i didn't even knew that there are specific patch versions for the expansions until i noticed them on the download page in the gog library. to my knowledge, this is a first and quite confusing for those who use the gog downloader. i mean... there are
FOUR (!) different iterations of one patch. one for the base game, one for the dlc files and one for each of the expansions.
this problem should be addressed by releasing one cumulative patch consistent of all prior updates or at least add these necessary files to the gog downloader page. or save yourself some time and make the GOTY version installer available to those who already own the base game and both expansions. this is a clusterfuck.