Unable to add images and files via Git

Whenever I try to add files to the "Files" folder I get the following error (I'm using GitHub Desktop):

"The remote disconnected. Check your Internet connection and try again."

It handles all new text files just fine, but if I try to add a png, jpg, or zip it gets rejected and I get an error.

How can I get blog.im to host my images?

UPDATE: I'm also getting a "500 Internal Server Error" when I try to upload a small jpg via the dashboard here - https://blot.im/dashboard/USERNAME/photo