Renders the `core/post-author` block on the server.

function render_block_core_post_author( $attributes, $content, $block ) {
	if ( ! isset( $block->context['postId'] ) ) {
		$author_id = get_query_var( 'author' );
	} else {
		$author_id = get_post_field( 'post_author', $block->context['postId'] );
	}

	if ( empty( $author_id ) ) {
		return '';
	}

	$avatar = ! empty( $attributes['avatarSize'] ) ? get_avatar(
		$author_id,
		$attributes['avatarSize']
	) : null;

	$byline  = ! empty( $attributes['byline'] ) ? $attributes['byline'] : false;
	$classes = array_merge(
		isset( $attributes['itemsJustification'] ) ? array( 'items-justified-' . $attributes['itemsJustification'] ) : array(),
		isset( $attributes['textAlign'] ) ? array( 'has-text-align-' . $attributes['textAlign'] ) : array()
	);

	$wrapper_attributes = get_block_wrapper_attributes( array( 'class' => implode( ' ', $classes ) ) );

	return sprintf( '
', $wrapper_attributes ) .
	( ! empty( $attributes['showAvatar'] ) ? '
' . $avatar . '
' : '' ) .
	'
' .
	( ! empty( $byline ) ? '
' . wp_kses_post( $byline ) . '
' : '' ) .
	'
' . get_the_author_meta( 'display_name', $author_id ) . '
' .
	( ! empty( $attributes['showBio'] ) ? '
' . get_the_author_meta( 'user_description', $author_id ) . '
' : '' ) .
	'
' .
	'
';
}