fix cbz import

oml/media/__init__.py

@@ -34,7 +34,7 @@ def metadata(f, from_=None):
     data['size'] = os.stat(f).st_size
 
     try:
-        if ext == 'cbr':
+        if ext in ('cbr', 'cbz'):
             info = cbr.info(f)
         elif ext in ('epub', 'kepub'):
             info = epub.info(f)
@@ -43,6 +43,9 @@ def metadata(f, from_=None):
             info = pdf.info(f)
         elif ext == 'txt':
             info = txt.info(f)
+        else:
+            logger.error('unknown extension %s', f, ext)
+            info = {}
     except:
         logger.debug('failed to load %s info from %s', ext, f, exc_info=True)
         info = {}