Fix/improve get last spotify event

addon.xml

 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
 <addon id="script.spotify.screensaver"
     name="Spotify Screensaver"
-    version="0.0.4"
+    version="0.0.5"
     provider-name="Benoît Harrault">
     <requires>
         <import addon="xbmc.python" version="2.25.0"/>

gui.py

@@ -117,7 +117,7 @@ class GUI(xbmcgui.WindowXMLDialog):
         event_type = event_split[1]
         event_value = event_split[2] if len(event_split) > 2 else ''
 
-        if event_type == 'change' or event_type == 'playing':
+        if event_type == 'changed' or event_type == 'playing':
             self._reload_images(event_value)
             self.next = True
         elif event_type == 'preloading':
@@ -164,7 +164,7 @@ class GUI(xbmcgui.WindowXMLDialog):
                 xbmcgui.ListItem(track_name, thumbnailImage=image_url)
             )
         except Exception as e:
-            self.log('failed to get track data ' + e.toString(), xbmc.LOGERROR)
+            self.log('failed to get track data ' + str(e), xbmc.LOGERROR)
 
         return imageLST
 
@@ -179,6 +179,7 @@ class GUI(xbmcgui.WindowXMLDialog):
         self.close()
 
     def _get_last_spotify_event(self):
+        last_event = ''
         try:
             f = open(LIBRESPOT_EVENT_FILE, 'r')
             last_event = f.readlines()[-1]