spt keeps returning to error when I connect to Sonos

The Sonos box is not detected by spt. This is handled in #426.

When I change the device with another Spotify player to my Sonos box, spt shows an extensive error message, which I can't copy/paste: a convert failure due to a null. The only variable that seems to be null is context.

There is a prompt to "click esc to return", but when I do that, it shows the main window shortly and immediately returns to the error message. This means that I can't control spt in any way anymore when a song is played from my Sonos speaker, and I have to return to the standard Spotify player.

I'm willing to help resolve this issue, but I will need guidance.