Upgrade/Install: Adjust the check for missing extensions during an upgrade so it remains compatible with versions of WordPress prior to 5.1.

The `WP_Error::has_errors()` method was introduced in WordPress 5.1, so this change uses its internal logic instead to remain compatible with earlier versions.

Props swissspidy, joemcgill, desrosj.

Fixes #63052

git-svn-id: https://develop.svn.wordpress.org/trunk@59956 602fd350-edb4-49c9-b593-d223f7449a82

.github/workflows/upgrade-develop-testing.yml

@@ -63,13 +63,17 @@ jobs:
         php: [ '7.2', '8.4' ]
         db-type: [ 'mysql' ]
         db-version: [ '5.7', '8.4' ]
-        wp: [ '6.5', '6.6', '6.7' ]
+        # WordPress 4.9 is the oldest version that supports PHP 7.2.
+        wp: [ '4.9', '6.5', '6.6', '6.7' ]
         multisite: [ false, true ]
 
         exclude:
           # The PHP <= 7.3/MySQL 8.4 jobs currently fail due to mysql_native_password being disabled by default. See https://core.trac.wordpress.org/ticket/61218.
           - php: '7.2'
             db-version: '8.4'
+          # WordPress 4.9 does not support PHP 8.4.
+          - php: '8.4'
+            wp: '4.9'
     with:
       os: ${{ matrix.os }}
       php: ${{ matrix.php }}

src/wp-admin/includes/update-core.php

@@ -1199,7 +1199,7 @@ function update_core( $from, $to ) {
 		}
 
 		// Add a warning when required PHP extensions are missing.
-		if ( $missing_extensions->has_errors() ) {
+		if ( ! empty( $missing_extensions->errors ) ) {
 			return $missing_extensions;
 		}
 	}