Fix Podcast Description None

Error occurs when saving changes to sqlite DB when desc is None, as SQL field "description" is set "NOT NULL" in table "podcasts".  Desc must be empty string not None.

src/gpodder/util.py

@@ -1009,7 +1009,10 @@ def get_first_line(s):
     Returns only the first line of a string, stripped so
     that it doesn't have whitespace before or after.
     """
-    return s.strip().split('\n')[0].strip()
+    try:
+        return s.strip().split('\n')[0].strip()
+    except:
+        return ''
 
 
 def object_string_formatter(s, **kwargs):