code: function renderServerError( err, req, res, next ) {
  	if ( process.env.NODE_ENV !== 'production' ) {
  		console.error( err );
  	}
  
  	const target = getBuildTargetFromRequest( req );
  
  	res.status( err.status || 500 );
  	const ctx = {
  		urls: generateStaticUrls( target ),
  		faviconURL: config( 'favicon_url' ),
  	};
  	res.send( renderJsx( '500', ctx ) );
  }
docs: /* We don't use `next` but need to add it for express.js to
  recognize this function as an error handler, hence the
  eslint-disable. eslint-disable-next-line no-unused-vars