Fixing some Tab/UnderlineNav Link types.

[dmarcey]

I tried out the UnderlineNav and TabNav in a TypeScript app (create-react-app --typescript) and ran into some issues related to the types of the Links.

This PR cleans them up, as well as the propTypes on the UnderlineNav.Link and TabNav.Link

Merge checklist

• Changed base branch to release branch
• Add or update TypeScript definitions (index.d.ts) if necessary
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge

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[colebemis]

Awesome 💯 Thanks for updating this! Just left one comment about href.

[colebemis]

Suggested change

	href: string
	href?: string

Should href be optional?

Reach Router's Link component accepts a to prop instead of href. If someone does something like this:

<UnderlineNav.Link as={ReachLink} to="#" />

will it cause a TypeError?

[dmarcey]

Yep, I think it will. I was going for consistency with LinkProps where it is also required.

export interface LinkProps extends CommonProps, TypographyProps {
  href: string
  underline?: boolean
}

Do we want that to be optional as well, in case someone wanted to do:

<Link as={ReachLink} to="#" />
?

[colebemis]

Yeah, that's a good idea.

[colebemis]

Looks good to me! 👍 I wanna let @emplums take a look at this too before we merge it. She'll be back next week.

[emplums]

This looks good to me, thanks @dmarcey!