AttributeError: 'NoneType' object has no attribute 'iter_content'

[metarmask]

Traceback (most recent call last):
  File "reddwall.py", line 264, in NextWallpaper
    wallpaper.set_wallpaper_request(self.UntilValidImageUrl())
  File "/home/metarmask/Downloads/reddwall-0.2/detools/wallpaper.py", line 125, in set_wallpaper_request
    for chunk in request.iter_content(4096):
AttributeError: 'NoneType' object has no attribute 'iter_content'

Got this error after clicking "Next Wallpaper". My OS is Linux Mint 17.2 Cinnamon 64-bit.

Here are my preferences:
Select from 'top'
from 'wallpapers'
containing search terms ''
with at least '2500' upvotes
from past 'week'
and update the wallpaper every '1' hours

• Allow NSFW wallpapers?