Spotify Web SDK Error "EMEError: No supported keysystems was found"

I literally copied and pasted the Spotify example code and pasted this in my /public/index.html file of my React + Electron project

...
   <title>React App</title>
</head>
   <body>
      <noscript>You need to enable JavaScript to run this app.</noscript>
      <script src="https://sdk.scdn.co/spotify-player.js"></script>
         <script>
            window.onSpotifyWebPlaybackSDKReady = () => {
               const token = '<access token>';
               const player = new Spotify.Player({
                  name: 'Web Playback SDK Quick Start Player',
                  getOAuthToken: cb => { cb(token); }
               });

               // Error handling
               player.addListener('initialization_error', ({ message }) => { console.error(message); });
               player.addListener('authentication_error', ({ message }) => { console.error(message); });

...

And I get this error:

Uncaught (in promise) EMEError: No supported keysystem was found.     index.js:18

followed by a

Failed to initialize player