YouTube Music Desktop

There is no official Desktop-App for YouTube Music.
Google Play Music Desktop Player exists but it uses a lot of resources on my laptop, is kinda slow and doesn't use Windows Close-, Maximize- and Minimize-Buttons, they use their own design.
So I decided to make my own Desktop-Player for YouTube Music.
I made an Electron-BrowserWindow which just displays the YouTube or YouTube Music Webpage, found the classes or ID's of the "Play"-, "Forward"- and "Backward"-Buttons on the YouTube Page in the DOM-Inspector and registered global keybindings for the media-keys in Electron. Whenever one of these keys is pressed, Electron executes some JavaScript on the Webpage. Just a simple click on the corresponding Button.
Now I finally have a lightweight YouTube Music Desktop-App.

Unfortunately, it doesn't work as expected...

The Code