Edit: The issue has been fixed in the new installer

Original post:
Running the GOG uninstaller for Nosferatu, even with the option to keep saved games removes some important files that makes it impossible to re-load the save files for a future installation. Uninstalling the game leaves only savegame#.fxa files, but the game seems to require at a minimum MenuSaveSlot#.fxa files that are located in the same folder in order to be able to re-load games. There are also screenshot thumbnails saved as Menu_SaveSlot_#.tga files that are not required. Make sure you copy those files before running the uninstaller if you want to keep your saved games. Luckily I'm cautious about these kinds of things and so my saves weren't lost but I wanted to let the community know just in case. I've already informed support of the issue, hopefully they'll create a new uninstaller soon enough.