Comment 7 for bug 1682919

I tried something and for me it seems to be working now.

Go to line 2027 and disable the check that gives that error (I do not see fit to check some image size on startup, it makes no sense anyway); it should look like this:
` """if not isinstance(size, (list, tuple)):
  raise ValueError("Size must be a tuple")
 """`

I am not sure everything will be working, but for me, it did start, shrink a folder of pictures and added the watermark.