Step 43 description tells that If userData.currentSong is null, set it to Play.
But the steps in console wrongfully tell:
When userData.currentSong is null, setPlayButtonAccessibleText should set the aria-label attribute of the play button to Play followed by a space and title of the first song in your playlist.
Thank you for reporting it, that does seem like a mistake. I opened an issue for it.
For future reference:
Bugs can be reported as GitHub Issues. Whenever reporting a bug, please check first that there isn’t already an issue for it and provide as much detail as possible.