fix(InteriorLeftNav): always pass a function (#253)
fix(InteriorLeftNav): always pass a function (#253)

onClick requires a function, but was sometimes getting `false`.
This follows the same pattern, but returns a no-op instead of
false to avoid a warning.

close #252
carbon-design-system/carbon-components-react,carbon-design-system/carbon-components,carbon-design-system/carbon-components,carbon-design-system/carbon-components-react,carbon-design-system/carbon-components,hellobrian/carbon-components-react,jzhang300/carbon-components-react,hellobrian/carbon-components-react,joshblack/carbon-components-react,joshblack/carbon-components-react