Do not fail if expected list config is of NoneType

[OrkoHunter]

https://github.com/SwagLyrics/SwagLyrics-For-Spotify/blob/456a5cfae242ca8f7a28a3d849a062b61e9f478c/.pep8speaks.yml#L7-L10

flake8:  # Same as scanner.linter value. Other option is flake8
    max-line-length: 120  # Default is 79 in PEP 8
    ignore:  # Errors and warnings to ignore

flake8.ignore is supposed to be a list. A config like this in yaml, produces a NoneType and results in error.

Thank you @aadibajpai for raising the issue!

[auto-comment]

💖 Thank you so much for creating the pull request! 💖

Have a look at the test workflow. The branch of this pull request is going to be deployed on Heroku with payload URL https://pep8speaks-pr-xxx.herokuapp.com . The repository https://github.com/OrkoHunter/test-pep8speaks is configured to test review deployments like this.

@OrkoHunter Create a review app for this PR on Heroku and update the Webhook URL of the test-pep8speaks app. Finally restart Travis to test this PR.
Remember to redeploy the production app and revert the Webhook URL when the Pull Request is merged.