src/vs/workbench/contrib/remote/browser/tunnelView.ts/error
	function error(notificationService: INotificationService, tunnel: RemoteTunnel | void, host: string, port: number) {
		if (!tunnel) {
			notificationService.warn(nls.localize('remote.tunnel.forwardError', "Unable to forward {0}:{1}. The host may not be available or that remote port may already be forwarded", host, port));
		}
	}