Circular table entry in GIF file

[JChristensen]

 * Xviewer version: Xviewer 1.6.1
 * Distribution: Linux Mint 18.3 Sylvia, Cinnamon 64-bit

Issue
When opening file, Xviewer says, "Could not load image 'animate.gif'. Circular table entry in GIF file"

Steps to reproduce

1. Download https://s.w-x.co/staticmaps/wu/wxtype/none/usa/animate.png (or see attached file)

2. Rename file to "animate.gif" (it really is a gif file despite the name)

3. Open file with Xviewer

Expected behaviour
File opens and displays properly.

Other information
File opens OK with other programs, e.g. GIMP, Firefox, etc.

Example file

[JChristensen]

PS: I also tried Xviewer 2.0.2 while running LM19.1 from live USB. The file still will not open, but the error message is different: "GIF image loader cannot understand this image."