Fails on start with empty protections.wordlist.words list

[MurzNN]

Describe the bug
When the protections.wordlist.words list is empty in YAML config file, mjolnir failts to start with this error:

mjolnir/lib/protections/WordList.js:35
         this.badWords = new RegExp("(" + config_1.default.protections.wordlist.words.join(")|(") + ")", "i");
TypeError: Cannot read property 'join' of null

To Reproduce
Steps to reproduce the behavior:

1. Comment-out all lines from protections.wordlist.words values in example config.
2. Try to start mjolnir

Expected behavior
Empty list should be treated as empty, without fatal errors.

[hanseartic]

as a quick-fix you can assign an empt array:
protections.wordlist.words: []