error while running under windows/wsl

[syffs]

I'm running this script on Windows/WSL and getting this error:

node_modules/fontello-cli/bin/fontello-cli --config ./config/fontello.json --css ./assets/css --font ./assets/fonts "open"

(node:31311) UnhandledPromiseRejectionWarning: Error: spawn wslvar ENOENT
    at Process.ChildProcess._handle.onexit (internal/child_process.js:267:19)
    at onErrorNT (internal/child_process.js:469:16)
    at processTicksAndRejections (internal/process/task_queues.js:84:21)

It only happens with open, install command works fine. It's failing in fontello.js on

open(sessionUrl)

It might be a good idea to catch any error and then output the url to browse manually ?