Iis_app undefined method 'empty?'

Chef InSpec
1

Opened a Chef Workstation PowerShell window (on Windows 10) to run inspec-shell on remote nodes.

inspec shell -t winrm://admin:pass@nodename

This shows the inspec> prompt, where I run:

describe iss_app('FOLDER', 'Default Web Site/') do
it { should exist }
end

Shows error:

iis_app 'Default Web Site/FOLDER'
[FAIL] should exist
undefined method `empty?' for nil:NilClass

Running C:\Windows\System32\inetsrv\appcmd list app shows the site and path as expected.

The client is running Windows 2008 R1. Is it supported?

PS. Other tests do work, including mssql_session.query(..)