Js-lingui: Support comments inside JSX macros by ignoring empty jsx expressions

[ckknight]

Describe the bug
When using a <Trans> element with a nested element like {/* This is a comment */}, it complains of @lingui/macro: Property value of ObjectProperty expected node to be of a type ["Expression","PatternLike"] but instead got "JSXEmptyExpression" Learn more: https://www.npmjs.com/package/@lingui/macro

To Reproduce
Steps to reproduce the behavior, possibly with minimal code sample, e.g:

import { Trans } from "@lingui/macro"

export default function App() {
   return (<Trans>
    {/* TODO: Come up with a better translation than this */}
    This should be translated!
  </Trans>)
}

Expected behavior
The comment should be ignored completely, leaving just the "This should be translated!" text.

Additional context
Add any other context about the problem here.

• jsLingui version 2.9.1
• Babel version [email protected]
• Your Babel config (e.g. .babelrc) or framework you use (Create React App, Meteor, etc.): Create React App

[tricoder42]

@ckknight Yeah, that's a good point! Willing to dive in and send a PR? If so, please use next branch as a base.

[ckknight]

@tricoder42 yep, I'm on it.