RSS block: check for description field before rendering excerpt (#66985)

* Check for description before passing to html_entity_decode
* Check author field

Co-authored-by: ramonjd <ramonopoly@git.wordpress.org>
Co-authored-by: aaronrobertshaw <aaronrobertshaw@git.wordpress.org>

packages/block-library/src/rss/index.php

@@ -61,17 +61,20 @@ function render_block_core_rss( $attributes ) {
 			$author = $item->get_author();
 			if ( is_object( $author ) ) {
 				$author = $author->get_name();
-				$author = '<span class="wp-block-rss__item-author">' . sprintf(
-					/* translators: byline. %s: author. */
-					__( 'by %s' ),
-					esc_html( strip_tags( $author ) )
-				) . '</span>';
+				if ( ! empty( $author ) ) {
+					$author = '<span class="wp-block-rss__item-author">' . sprintf(
+						/* translators: byline. %s: author. */
+						__( 'by %s' ),
+						esc_html( strip_tags( $author ) )
+					) . '</span>';
+				}
 			}
 		}
 
-		$excerpt = '';
-		if ( $attributes['displayExcerpt'] ) {
-			$excerpt = html_entity_decode( $item->get_description(), ENT_QUOTES, get_option( 'blog_charset' ) );
+		$excerpt     = '';
+		$description = $item->get_description();
+		if ( $attributes['displayExcerpt'] && ! empty( $description ) ) {
+			$excerpt = html_entity_decode( $description, ENT_QUOTES, get_option( 'blog_charset' ) );
 			$excerpt = esc_attr( wp_trim_words( $excerpt, $attributes['excerptLength'], ' [&hellip;]' ) );
 
 			// Change existing [...] to [&hellip;].