Got the same problem with installation of Xubuntu 16.04. Until now I've never had that problem. libgstapp-0.10.so.0 really should be included to the installation file. Not everybody has the skills and time to seek for information to get help.
Found a solution: sudo add-apt-repository ppa:dhor/myway ...
Added the sample file as 7zip file.
Maybe I should mention, that all my gif files once have been jpg files, cropped and converted by XnView classic, but many versions ago.
Take a GIF image and open it, setting (Edit, Background color...) is unchanged (RGB: 255,255,255 = white), now mark a field per mouse and press DEL. The deleted field appears in black instead in white. This doesn't appear on JPG or PNG images. Weird is that this doesn't happen with every GIF image ...
Until now this problem occurs with every GIF image that I wanted to edit in the mentiond way. The source file was a JPG image that got converted into GIF to reduce file size, done with XnView (but can't recall which version that was).
On a Linux host runs Oracle VM VirtualBox with Windows XP . When editing any GIF image with XnView (2.31) , the image file gets destroyed . Problem appears on both systems, inside the VM and from VM to Linux. (XnView MP on Linux runs fine with editing GIF files.)