Index: wp-content/themes/twentyseventeen/inc/template-tags.php
===================================================================
--- wp-content/themes/twentyseventeen/inc/template-tags.php	(revision 58954)
+++ wp-content/themes/twentyseventeen/inc/template-tags.php	(working copy)
@@ -152,13 +152,14 @@
 	// Only when in Customizer, use a placeholder for an empty panel.
 	$show_panel_placeholder = false;
 
-	global $post; // Modify the global post object before setting up post data.
-	if ( get_theme_mod( 'panel_' . $id ) ) {
-		$post = get_post( get_theme_mod( 'panel_' . $id ) );
-		setup_postdata( $post );
+	// Retrieve the post associated with the panel ID.
+	$panel_post = get_post( get_theme_mod( 'panel_' . $id ) );
+
+	if ( $panel_post ) {
+		setup_postdata( $panel_post );
 		set_query_var( 'panel', $id );
 
-		if ( $post && in_array( $post->post_status, array( 'publish', 'private' ), true ) ) {
+		if ( in_array( $panel_post->post_status, array( 'publish', 'private' ), true ) ) {
 			get_template_part( 'template-parts/page/content', 'front-page-panels' );
 		} elseif ( is_customize_preview() ) {
 			$show_panel_placeholder = true;