Index: src/wp-admin/includes/ajax-actions.php
===================================================================
--- src/wp-admin/includes/ajax-actions.php	(revision 29542)
+++ src/wp-admin/includes/ajax-actions.php	(working copy)
@@ -2719,12 +2719,18 @@
 
 	ob_start();
 
+	$shortcode = do_shortcode( wp_unslash( $_REQUEST['shortcode'] ) );
+
+	if ( empty( $shortcode ) ) {
+		wp_send_json_error( array( 'statusText' => __( 'No items found.' ) ) );
+	}
+
 	$styles = wp_media_mce_styles();
 	foreach ( $styles as $style ) {
 		printf( '<link rel="stylesheet" href="%s"/>', $style );
 	}
 
-	echo do_shortcode( wp_unslash( $_REQUEST['shortcode'] ) );
+	echo $shortcode;
 
 	if ( ! empty( $wp_scripts ) ) {
 		$wp_scripts->done = array();