Problem capturing data with Yslow CLI

I'm trying to run the Yslow report on a HAR that I captured using Chrome DevTools. The HAR appears to be valid (I've opened it fine using other non-CLI tools).

Steps I've taken:

1. npm install yslow
2. yslow --help (to make sure the package is installed and functioning).
3. yslow cloud-output.har

Result: [TypeError: Cannot call method 'getElementsByTagName' of undefined]

Any thoughts?

Not sure if this is significant, but in the help, "yslow" is replaced with "undefined":

Examples:

undefined file.har
undefined -i grade -f xml -b http://server.com/beacon file1.har file2.har
undefined -info all --format plain /tmp/*.har
undefined -i basic --rulseset yslow1 -d < file.har
curl example.com/file.har | undefined -i grade -b http://server.com/beacon -v

Is there any progress here ?

Ping! I have the same issue! Did anyone find a solution yet?