SongPal: do not crash if active_source is not (yet) available - fixes #20343 (#20344)

* SongPal: error handling if active_source can't be detected

* sonpal: Add comment to the use of getattr() for property source

* songpal: make comment single-line

homeassistant/components/media_player/songpal.py

@@ -288,7 +288,8 @@ class SongpalDevice(MediaPlayerDevice):
     @property
     def source(self):
         """Return currently active source."""
-        return self._active_source.title
+        # Avoid a KeyError when _active_source is not (yet) populated
+        return getattr(self._active_source, 'title', None)
 
     @property
     def volume_level(self):