When start playing an empty playlist, the currently playing song is stopped and the new playlist is loaded. The new playlist does not contain any song, therefore no music is playing.
There’s no unwanted silence from mistakenly starting an empty playlist.
Additional description and context
I thought about it if it actually provides any real value since optimally you do not have empty playlists and if, you learn that you should not have them and star playing them, basically you get punished for starting an empty playlist which is kind of good education.
I just created a smart playlist which should contain all 5 star items yet the playlist is empty. Neither grid nor list view shows the amount of songs within the playlist. Therefore, it’s very easy to start an empty playlist without knowing it in advance.
I have not yet checked it but this could also be a problem for the online/offline case where you end up with an empty playlist because no song is cached on the phone.