Fix issues reported by codacy

mycroft/audio/main.py

@@ -462,13 +462,13 @@ def main():
             message = json.dumps(_message)
         except (KeyboardInterrupt, SystemExit):
             raise
-        except Exception:
-            pass
+        except Exception as e:
+            LOG.exception(e)
         LOG.debug(message)
 
     LOG.info("Staring Audio Services")
     ws.on('message', echo)
-    audio_service = AudioService(ws)
+    AudioService(ws)  # Connect audio service instance to message bus
     try:
         ws.run_forever()
     except KeyboardInterrupt as exc:

mycroft/skills/audioservice.py

@@ -55,12 +55,13 @@ class AudioService():
         """
         self.info = message.data
 
-    def queue(self, tracks=[]):
+    def queue(self, tracks=None):
         """ Queue up a track to playing playlist.
 
             Args:
                 tracks: track uri or list of track uri's
         """
+        tracks = tracks or []
         if isinstance(tracks, basestring):
             tracks = [tracks]
         elif not isinstance(tracks, list):
@@ -69,7 +70,7 @@ class AudioService():
         self.emitter.emit(Message('mycroft.audio.service.queue',
                                   data={'tracks': tracks}))
 
-    def play(self, tracks=[], utterance=''):
+    def play(self, tracks=None, utterance=''):
         """ Start playback.
 
             Args:
@@ -77,6 +78,7 @@ class AudioService():
                 utterance: forward utterance for further processing by the
                            audio service.
         """
+        tracks = tracks or []
         if isinstance(tracks, basestring):
             tracks = [tracks]
         elif not isinstance(tracks, list):