print-failing generate list with 'null' as value

[panthony]

Using:

• ember@3.4.4
• ember-cli-template-lint@1.0.0-beta.2

I'm trying to use ember template-lint:print-failing with the following rules:

  rules: {
    'no-bare-strings': true,
    'attribute-indentation': false,
    'no-inline-styles': false
  },

And I get lots of entries like this:

  {
    "moduleId": "my-app/components/my-component/template",
    "only": [
      null
    ]
  },

Where the offending rule would have been attribute-indentation.