Error on wide aspect ratio image

[Marcin]

I'm trying to run script on 768 x 256 resolution img.
After creating firs img and upscaling once I'm getting this:

0 NVIDIA GeForce GTX 1070] queueC=2[8] queueG=0[16] queueT=1[2]
[0 NVIDIA GeForce GTX 1070] bugsbn1=0 bugbilz=0 bugcopc=0 bugihfa=0
[0 NVIDIA GeForce GTX 1070] fp16-p/s/a=1/1/0 int8-p/s/a=1/1/1
[0 NVIDIA GeForce GTX 1070] subgroup=32 basic=1 vote=1 ballot=1 shuffle=1
0,00%
12,50%
25,00%
37,50%
50,00%
62,50%
75,00%
87,50%
Passes: 0%| | 0/1 [00:04<?, ?it/s]
Traceback (most recent call last):
File "scripts/txt2imghd.py", line 510, in
main()
File "scripts/txt2imghd.py", line 329, in main
text2img2(opt)
File "scripts/txt2imghd.py", line 442, in text2img2
slices, _ = grid_slice(source_image, gobig_overlap, og_size, False)
File "scripts/txt2imghd.py", line 184, in grid_slice
coordinates, new_size = grid_coords(source.size, og_size, overlap)
File "scripts/txt2imghd.py", line 146, in grid_coords
last_coordx, last_coordy = dy_list[-1:][0]
IndexError: list index out of range`

Things work normally when I decrease width to 512px.
Is it "too wide" for img2img.py to run properly on pieces of the original?