Editor: Fix conditionals in Template Editing Mode.

Previously, Site Editor client-side routing started using only the path query argument for loading non-editor views. The router removed the `postType` query 
argument, which caused an error message to be displayed when the template parts list page was reloaded.

This changeset fixes the issue as it was affecting hybrid themes.

Props Mamaduka, isabel_brison, ramonopoly.
Fixes #58889.




git-svn-id: https://develop.svn.wordpress.org/trunk@56302 602fd350-edb4-49c9-b593-d223f7449a82

Author: audrasjb

src/wp-admin/menu.php

@@ -210,7 +210,7 @@
 	$submenu['themes.php'][6] = array(
 		__( 'Template Parts' ),
 		'edit_theme_options',
-		'site-editor.php?postType=wp_template_part&path=/wp_template_part/all',
+		'site-editor.php?path=/wp_template_part/all',
 	);
 }
 

src/wp-admin/site-editor.php

@@ -23,7 +23,10 @@
 	wp_die( __( 'The theme you are currently using is not compatible with the Site Editor.' ) );
 }
 
-$is_template_part_editor = isset( $_GET['postType'] ) && 'wp_template_part' === sanitize_key( $_GET['postType'] );
+$is_template_part = isset( $_GET['postType'] ) && 'wp_template_part' === sanitize_key( $_GET['postType'] );
+$is_template_part_path = isset( $_GET['path'] ) && 'wp_template_partall' === sanitize_key( $_GET['path'] );
+$is_template_part_editor = $is_template_part || $is_template_part_path;
+
 if ( ! wp_is_block_theme() && ! $is_template_part_editor ) {
 	wp_die( __( 'The theme you are currently using is not compatible with the Site Editor.' ) );
 }