Linux, Go 1.7.3 and 1.7.4 (official binary), st terminal.
$ gifter examplers/nyan.gif
panic: runtime error: integer divide by zero
goroutine 7 [running]:
panic(0x5072c0, 0xc420010150)
/home/livibetter/var/bin/go/src/runtime/panic.go:500 +0x1a1
main.(*GifImg).CellAvgRGB(0xc4200e6080, 0xc4200e6000, 0x0, 0x8000000000000000, 0x8000000000000000, 0x8000000000000000, 0x0, 0x0, 0x0)
/tmp/tgo/src/github.com/esimov/gifter/image.go:48 +0x25c
main.draw.func2(0xc4200e6000, 0xc420106000, 0xc420106008, 0xc420106010, 0xc420106018, 0x7ff0000000000000, 0x7ff0000000000000, 0xc400000000, 0x0)
/tmp/tgo/src/github.com/esimov/gifter/main.go:179 +0x193
created by main.draw
/tmp/tgo/src/github.com/esimov/gifter/main.go:194 +0x3f8
I don't know much of Go, so if anything more information you need from me, you might need to instruct me with explicit commands.