"puppet ls" exits with "Error: undefined method `split' for nil:NilClass" for some paths

"rel_path" seems to be "nil" for some reason.

If it is nil, it seems safer to skip to next file in list, and not try to do a split.

before change:

    # puppet ls /etc/systemd/system
    Error: undefined method `split' for nil:NilClass
    Error: Try 'puppet help ls list' for usage

    # puppet ls /etc/systemd/system -r
    nagios-nrpe-server.service
      declared in /srv/puppet/env/production/legacy-modules/site/systemd/manifests/unit.pp:15
      content from a "content" parameter

after change:

    # puppet ls /etc/systemd/system -r
    nagios-nrpe-server.service
      declared in /srv/puppet/env/production/legacy-modules/site/systemd/manifests/unit.pp:15
      content from a "content" parameter
    # puppet ls /etc/systemd/system
    nagios-nrpe-server.service
      declared in /srv/puppet/env/production/legacy-modules/site/systemd/manifests/unit.pp:15
      content from a "content" parameter

The content of  "puppet ls / -r" is the same before and after.