Handle null `platform.os.family`.
Handle null `platform.os.family`.

This occurs for certain OSes, like Chrome OS.

Per platform documentation[0], `platform.os.family` can be a string OR `null`.

[0] https://github.com/bestiejs/platform.js/blob/master/doc/README.md#platformosfamily
avocode/react-shortcuts,avocode/react-shortcuts