// On macOS, the system enforces single instance automatically when users try to open a second instance of your app in Finder, and the open-file and open-url events will be emitted for that.
// However when users start your app in command line, the system's single instance mechanism will be bypassed, and you have to use this method to ensure single instance.
// This can be tested with one terminal: npx electron .
// and another terminal: npx electron . path/to/file.mp4