Fix get track data

addon.xml

 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
 <addon id="script.spotify.screensaver"
     name="Spotify Screensaver"
-    version="0.0.6"
+    version="0.0.7"
     provider-name="Benoît Harrault">
     <requires>
         <import addon="xbmc.python" version="2.25.0"/>

gui.py

@@ -153,16 +153,21 @@ class GUI(xbmcgui.WindowXMLDialog):
             )
             data = response.json()
 
-            track_name = data['name']
+            track_name = data.get('name', '')
 
             # album/track image
-            album = data['album']
-            images = album['images']
-            image_url = images[0]['url']
-
-            imageLST.append(
-                xbmcgui.ListItem(track_name, thumbnailImage=image_url)
-            )
+            album = data.get('album')
+            if album is not None:
+                images = album.get('images')
+                if images is not None:
+                    image = images[0]
+                    if image is not None:
+                        image_url = image.get('url')
+                        if image_url is not None:
+                            imageLST.append(
+                                xbmcgui.ListItem(
+                                    track_name, thumbnailImage=image_url)
+                            )
         except Exception as e:
             self.log('failed to get track data ' + str(e), xbmc.LOGERROR)