Comply with STYLEGUIDE.md not using unset but declared identifiers and set to `null`

* See [here](https://github.com/OpenUserJs/OpenUserJS.org/commit/0263c797d323cdf76be9cd6f11093903ea250b69#diff-ba2dc84c4bcbe54f368b6c7d3bc1b13eR28)

Applies to #189