This plotdigitizer cannot work in some images

[chunfang2001]

I had getting out the line of the graph
The command I use is
plotdigitizer output/test.png -p 0,0 -p 150,0 -p 0,0 -p 0,7.5 -l 50,10 -l 100,10 -l 50,10 -l 50,160 --plot test.png

But I face this error
INFO:root:Extracting trajectories from output\test.png INFO:root:[(50, 10), (100, 10), (50, 10), (50, 160)] → origin 50, 10 INFO:root: 253.37610016420362 3.9020312040091025 Traceback (most recent call last): File "C:\Users\chunfang\anaconda3\envs\weather_nowcast\lib\runpy.py", line 194, in _run_module_as_main return _run_code(code, main_globals, None, File "C:\Users\chunfang\anaconda3\envs\weather_nowcast\lib\runpy.py", line 87, in _run_code exec(code, run_globals) File "C:\Users\chunfang\anaconda3\envs\weather_nowcast\Scripts\plotdigitizer.exe\__main__.py", line 7, in <module> File "C:\Users\chunfang\anaconda3\envs\weather_nowcast\lib\site-packages\plotdigitizer\plotdigitizer.py", line 323, in main run(args) File "C:\Users\chunfang\anaconda3\envs\weather_nowcast\lib\site-packages\plotdigitizer\plotdigitizer.py", line 264, in run traj = process_image(img_) File "C:\Users\chunfang\anaconda3\envs\weather_nowcast\lib\site-packages\plotdigitizer\plotdigitizer.py", line 217, in process_image trajcolor = params_["timeseries_colors"][0] IndexError: list index out of range

Can I know what error is it? Thanks