Neural-Style output flag - bash

Question

I'm messing around with jcjohnson/neural-style. I have it up and running just fine. However, I cannot for the life of me make the -output_image or -init flags work. My gut says it's some very simple misunderstanding on my part.
-output_image is driving me especially nuts because it should just be a string to use as the filename, the script even appends the file formate in function that takes -output_image as an argument. I've tried single, double, and no quotes, as well as changing the order of the flags. My gut says it's something trivially simple because nobody is complaining about this on-line anywhere,but I'm a little in over my head because I'm not especially proficient with either bash, torch, or lua.
I'm using this simple script I hacked together that works just fine if I leave off both of the troublesome flags
#!/bin/bash
echo "#### Starting Job B ####"
th neural_style.lua \
-gpu -1 \
-print_iter 1 \
-save_iter 10 \
-num_iterations 3000 \
-style_image a_style.jpg \
-content_image a_content.jpg \
-style_scale 0.15 \
-style_weight 25 \
-content_weight 1e3 \
-output_image a \
-init a_460.png \
The above throws "Invalid argument: "
if it helps, in the script 'neural_style.lua'
the flags are defined as
cmd:option('-init', 'random', 'random|image')
...
cmd:option('-output_image', 'out.png')
and used as
local function maybe_save(t)
local should_save = params.save_iter > 0 and t % params.save_iter == 0
should_save = should_save or t == params.num_iterations
if should_save then
local disp = deprocess(img:double())
disp = image.minmax{tensor=disp, min=0, max=1}
local filename = build_filename(params.output_image, t)
if t == params.num_iterations then
filename = params.output_image -- ## LOOK HERE ##
end
-- Maybe perform postprocessing for color-independent style transfer
if params.original_colors == 1 then
disp = original_colors(content_image, disp)
end
image.save(filename, disp) -- ## LOOK HERE ##
end
end
as well as
if params.init == 'random' then
img = torch.randn(content_image:size()):float():mul(0.001)
elseif params.init == 'image' then
img = content_image_caffe:clone():float()
else
error('Invalid init type') -- ## NOT THE ERROR THROWN #
end
if params.gpu >= 0 then