fix position

recommend.py

@@ -29,6 +29,9 @@ def video_position_recommend(mid, uid, app_type, videos):
     if pos2_vids is not None:
         pos2_vids = ast.literal_eval(pos2_vids)
 
+    pos1_vids = [] if pos1_vids is None else pos1_vids
+    pos2_vids = [] if pos2_vids is None else pos2_vids
+
     pos1_vids = [int(i) for i in pos1_vids]
     pos2_vids = [int(i) for i in pos2_vids]