Code Quality: Fix PHPStan undefined variables using isset/empty checks

Author: huzaifaalmesbah

src/wp-includes/ms-settings.php

@@ -33,10 +33,8 @@
  *                                  Use `get_current_network_id()` instead.
  * @global bool       $public       Deprecated. Whether the site found on load is public.
  *                                  Use `get_site()->public` instead.
- * @global string     $table_prefix Database table prefix.
- * @global wpdb       $wpdb         WordPress database abstraction object.
  */
-global $current_site, $current_blog, $domain, $path, $site_id, $public, $table_prefix, $wpdb;
+global $current_site, $current_blog, $domain, $path, $site_id, $public;
 
 /** WP_Network class */
 require_once ABSPATH . WPINC . '/class-wp-network.php';
@@ -101,9 +99,13 @@
 	wp_load_core_site_options( $site_id );
 }
 
-$wpdb->set_prefix( $table_prefix, false ); // $table_prefix can be set in sunrise.php.
-$wpdb->set_blog_id( $current_blog->blog_id, $current_blog->site_id );
-$table_prefix       = $wpdb->get_blog_prefix();
+if ( isset( $wpdb ) ) {
+	if ( isset( $table_prefix ) ) {
+		$wpdb->set_prefix( $table_prefix, false ); // $table_prefix can be set in sunrise.php.
+	}
+	$wpdb->set_blog_id( $current_blog->blog_id, $current_blog->site_id );
+	$table_prefix = $wpdb->get_blog_prefix();
+}
 $_wp_switched_stack = array();
 $switched           = false;
 

src/wp-settings.php

@@ -29,10 +29,8 @@
  * @global string[] $required_php_extensions The names of required PHP extensions.
  * @global string   $required_mysql_version  The minimum required MySQL version string.
  * @global string   $wp_local_package        Locale code of the package.
- * @global array    $wp_filter               WordPress filter hooks.
- * @global string   $table_prefix            Database table prefix.
  */
-global $wp_version, $wp_db_version, $tinymce_version, $required_php_version, $required_php_extensions, $required_mysql_version, $wp_local_package, $wp_filter, $table_prefix;
+global $wp_version, $wp_db_version, $tinymce_version, $required_php_version, $required_php_extensions, $required_mysql_version, $wp_local_package;
 require ABSPATH . WPINC . '/version.php';
 require ABSPATH . WPINC . '/compat-utf8.php';
 require ABSPATH . WPINC . '/compat.php';
@@ -102,7 +100,7 @@
 	include WP_CONTENT_DIR . '/advanced-cache.php';
 
 	// Re-initialize any hooks added manually by advanced-cache.php.
-	if ( $wp_filter ) {
+	if ( ! empty( $wp_filter ) ) {
 		$wp_filter = WP_Hook::build_preinitialized_hooks( $wp_filter );
 	}
 }
@@ -142,7 +140,7 @@
  *
  * @global string $table_prefix The database table prefix.
  */
-if ( ! isset( $GLOBALS['table_prefix'] ) ) {
+if ( ! isset( $GLOBALS['table_prefix'] ) && isset( $table_prefix ) ) {
 	$GLOBALS['table_prefix'] = $table_prefix;
 }