Description

This change allows compilation of _button-group.scss on libsass 3.6.3. Without this change @include foundation-button-group; will cause an infinite loop on compilers which use it. For example: PHP on Ubuntu 20.04. The change simply prevents the use of 'null' from being evaluated.

• Closes Button-group causes memory Leak #12070

Types of changes

• Documentation
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (anything that would change an existing functionality)
• Maintenance (refactor, code cleaning, development tools...)

Checklist

• I have read and follow the CONTRIBUTING.md document.
• The pull request title and template are correctly filled.
• The pull request targets the right branch (develop or develop-v...).
• My commits are correctly titled and contain all relevant information.
• I have updated the documentation accordingly to my changes (if relevant).
• I have added tests to cover my changes (if relevant).