Formatting: Skip readonly properties in map_deep() to prevent fatal errors on PHP 8.1+.

Author: himanshupathak95

src/wp-includes/formatting.php

@@ -5145,6 +5145,13 @@ function map_deep( $value, $callback ) {
 	} elseif ( is_object( $value ) ) {
 		$object_vars = get_object_vars( $value );
 		foreach ( $object_vars as $property_name => $property_value ) {
+			if ( PHP_VERSION_ID >= 80100 ) {
+				$reflection_property = new ReflectionProperty( $value, $property_name );
+				if ( $reflection_property->isReadOnly() ) {
+					continue;
+				}
+			}
+
 			$value->$property_name = map_deep( $property_value, $callback );
 		}
 	} else {