sol.file.open() doesn't use the right path
TL;DR : QuestFiles::get_full_quest_write_dir() tries to make the path based on the home path, in a way that doesn't work with Windows (places a / just after the home path, which already ends with a \, resulting in a \/in the final path)
When i call sol.file.open("filename"), which is supposed to open the file named "filename" in the quest writing directory, the path it tries to open is bugged :
In this precise case i called sol.file.open("settings.dat"). It seems like the engine wasn't able to get the full quest writing path, and more precisely to concatenate the $HOME directory and the solarus writing path ("/.solarus/<quest subdirectory>") correctly.
Furthermore, i get a different error message if i try to open a file that doesn't exist, so it seems like the engine was actually able to acess the directory to confirm that my file actually existed, but then failed to open it.
I don't have any problem with other file-opening functions, such as sol.game.load() or sol.main.load_settings(), so it seems the problem is really specific.