library: show album id in empty album error
This makes it possible to recover from this case, as you can correct
whatever caused it, by either fixing album ids on tracks or removing the
empty album id.
@@ -1119,7 +1119,7 @@ class Album(LibModel):
"""
item = self.items().get()
if not item:
- raise ValueError(u'empty album')
+ raise ValueError(u'empty album for album id %d' % self.id)
return os.path.dirname(item.path)
def _albumtotal(self):
