Customize: Prevent edge case fatal error when attempting to save changes to a changeset that had previously been corrupted.

Check return value of `WP_Customize_Manager::get_changeset_post_data()` and return if error instead of assuming it is an array.

Amends [38810].
See #30937.
Fixes #41252.

Built from https://develop.svn.wordpress.org/trunk@41012


git-svn-id: http://core.svn.wordpress.org/trunk@40862 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-wp-customize-manager.php

@@ -2263,6 +2263,9 @@ final class WP_Customize_Manager {
 			}
 
 			$existing_changeset_data = $this->get_changeset_post_data( $changeset_post_id );
+			if ( is_wp_error( $existing_changeset_data ) ) {
+				return $existing_changeset_data;
+			}
 		}
 
 		// Fail if attempting to publish but publish hook is missing.

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9-alpha-41011';
+$wp_version = '4.9-alpha-41012';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.