Plugin_Upgrader::delete_old_plugin( bool|WP_Error $removed, string $local_destination, string $remote_destination, array $plugin ): bool|WP_Error

675	public function delete_old_plugin( $removed, $local_destination, $remote_destination, $plugin ) {676		global $wp_filesystem;677 678		if ( is_wp_error( $removed ) ) {679			return $removed; // Pass errors through.680		}681 682		$plugin = $plugin['plugin'] ?? '';683		if ( empty( $plugin ) ) {684			return new WP_Error( 'bad_request', $this->strings['bad_request'] );685		}686 687		$plugins_dir     = $wp_filesystem->wp_plugins_dir();688		$this_plugin_dir = trailingslashit( dirname( $plugins_dir . $plugin ) );689 690		if ( ! $wp_filesystem->exists( $this_plugin_dir ) ) { // If it's already vanished.691			return $removed;692		}693 694		/*695		 * If plugin is in its own directory, recursively delete the directory.696		 * Base check on if plugin includes directory separator AND that it's not the root plugin folder.697		 */698		if ( strpos( $plugin, '/' ) && $this_plugin_dir !== $plugins_dir ) {699			$deleted = $wp_filesystem->delete( $this_plugin_dir, true );700		} else {701			$deleted = $wp_filesystem->delete( $plugins_dir . $plugin );702		}703 704		if ( ! $deleted ) {705			return new WP_Error( 'remove_old_failed', $this->strings['remove_old_failed'] );706		}707 708		return true;709	}