r client behavior, as it is represented as a
 * list in JSON rather than an object/map.
 *
 * @since 5.7.0
 *
 * @param WP_Error $error WP_Error instance.
 *
 * @return WP_REST_Response List of associative arrays with code and message keys.
 */
function rest_convert_error_to_response( $error ) {
	$status = array_reduce(
		$error->get_all_error_data(),
		static function ( $status, $error_data ) {
			return is_array( $error_data ) && isset( $error_data['status'] ) ? $error_data['status'] : $status;
		},
		500
	);

	$errors = array();

	foreach ( (array) $error->errors as $code => $messages ) {
		$all_data  = $error->get_all_error_data( $code );
		$last_data = array_pop( $all_data );

		foreach ( (array) $messages as $message ) {
			$formatted = array(
				'code'    => $code,
				'message' => $message,
				'data'    => $last_data,
			);

			if ( $all_data ) {
				$formatted['additional_data'] = $all_data;
			}

			$errors[] = $formatted;
		}
	}

	$data = $errors[0];
	if ( count( $errors ) > 1 ) {
		// Remove the primary error.
		array_shift( $errors );
		$data['additional_errors'] = $errors;
	}

	return new WP_REST_Response( $data, $status );
}

/**
 * Checks whether a REST API endpoint request is currently being handled.
 *
 * This may be a standalone REST API request, or an internal request dispatched from within a regular page load.
 *
 * @since 6.5.0
 *
 * @global WP_REST_Server $wp_rest_server REST server instance.
 *
 * @return bool True if a REST endpoint request is currently being handled, false otherwise.
 */
function wp_is_rest_endpoint() {
	/* @var WP_REST_Server $wp_rest_server */
	global $wp_rest_server;

	// Check whether this is a standalone REST request.
	$is_rest_endpoint = wp_is_serving_rest_request();
	if ( ! $is_rest_endpoint ) {
		// Otherwise, check whether an internal REST request is currently being handled.
		$is_rest_endpoint = isset( $wp_rest_server )
			&& $wp_rest_server->is_dispatching();
	}

	/**
	 * Filters whether a REST endpoint request is currently being handled.
	 *
	 * This may be a standalone REST API request, or an internal request dispatched from within a regular page load.
	 *
	 * @since 6.5.0
	 *
	 * @param bool $is_request_endpoint Whether a REST endpoint request is currently being handled.
	 */
	return (bool) apply_filters( 'wp_is_rest_endpoint', $is_rest_endpoint );
}