Hey!
Looking back, I realize I've missed a step. After Step 3 (navigating to the donsol-js-master folder in command promt), you should run the command: npm install electron-packager before going to Step 4 (which allows you to execute npm run build_win without getting an error). I will edit my post to add this.
Hopefully doing that will fix the problem. I think what's happening is that you're using Electron v25.1.1 to compile, and not v7.1.12 (the version defined at the end of the package.json file which should look like:
"devDependencies": {
"electron": "^7.1.12",
"electron-packager": "^14.2.1"
}
}
As a test, I changed "electron": "^7.1.12" to "electron": "^25.1.1" before running npm run build_win, and also ended up just getting a blank black window when running Donsol.exe. Considering Electron v7 came out the same year the code was last updated (2020 at the time of writing), I'm guessing the source code is referencing something that's depreciated in later versions of Electron.