Page List: Show empty placeholder if no items (#35441)

* Add empty response placeholder

* Return early if no top level pages

* Simplify placeholder to just span and text

* Move the check for empty pages up to all_pages

This makes it more clear and bails out even earlier.

packages/block-library/src/page-list/edit.js

@@ -154,6 +154,9 @@ export default function PageListEdit( {
 				<ServerSideRender
 					block="core/page-list"
 					attributes={ attributesWithParentStatus }
+					EmptyResponsePlaceholder={ () => (
+						<span>{ __( 'Page List: No pages to show.' ) }</span>
+					) }
 				/>
 			</div>
 		</>

packages/block-library/src/page-list/index.php

@@ -250,6 +250,12 @@ function render_block_core_page_list( $attributes, $content, $block ) {
 		)
 	);
 
+	// If thare are no pages, there is nothing to show.
+	// Return early and empty to trigger EmptyResponsePlaceholder.
+	if ( empty( $all_pages ) ) {
+		return;
+	}
+
 	$top_level_pages = array();
 
 	$pages_with_children = array();