Replace / characters in filenames

To avoid path issues, artist, album, and track names need to have any
`/` characters removed.

ripcd.py

@@ -47,6 +47,7 @@ RELEASE_INFO_TMPL = '{artist} - {title} ({year}): {more_info}'
 FILENAME_SAFE_MAP = {
     '’': "'",
     ':': ' - ',
+    '/': '-',
 }
 
 
@@ -239,7 +240,6 @@ def get_release_by_id(mbid):
             'labels',
         ],
     )
-    import pdb; pdb.set_trace()
     return res['release']
 
 
@@ -258,7 +258,10 @@ def get_release_list_from_device(device):
     if 'disc' in res:
         return res['disc']['release-list']
     else:
+        try:
             return res['release-list']
+        except KeyError:
+            return []
 
 
 def parse_date(datestr):
@@ -360,6 +363,9 @@ def main():
             release = prompt_select_release(release_list)
         elif len(release_list) == 1:
             release = release_list[0]
+        else:
+            sys.stderr.write('Could not find a matching MusicBrainz release\n')
+            raise SystemExit(1)
 
     print('Ripping', format_release(release))