fixed bug with playing without selecting a song

screens-test.py

@@ -326,6 +326,9 @@ class TextualSubpyPlayer(App):
         self.play_pause_song()
 
     def play_pause_song(self) -> None:
+        if not self.currently_playing:
+            return None
+
         if self.playing:
             self.place = pygame.mixer.music.get_pos()
             pygame.mixer.music.pause()