Yes that file is using G00 not G0
As you can see in the code of the optimizer, it is expecting G0.
You could change the source and run a local copy (which would take about 30 seconds) or your could change the file (which would be easy with sed).
You could also change the source of the code and submit a pull request on github to fix your situation, then I could submit the change to the main project and it would resolve the problem for others using G00 (this is how open source is supposed to work, not one developer doing everything). The issue is that the toolchain I use doesn't output G00 it outputs G0 so there's no real motivation for me to modify the code to support everyone's toolchain as the project pays nothing monetarily.
It sure would be nice if some of these behemoth's offered a chance for work, but the reality is that they don't so open source is a step by step project to replace the problem of decay in the normal business workflow caused by repetition and adding "features" just for the sake of adding features.
It's probably easier to just write a regex to convert your file from G00 to G0, really it is just s/G00/G0/g and done.
Andrew