private static void fail(ClientRequestContext ctx, Throwable cause) {
        final HttpRequest req = ctx.request();
        if (req != null) {
            req.abort(cause);
        }

        final RequestLogBuilder logBuilder = ctx.logBuilder();
        logBuilder.endRequest(cause);
        logBuilder.endResponse(cause);
    }
An undefined {@link URI} to create {@link WebClient} without specifying {@link URI}.
core/src/main/java/com/linecorp/armeria/internal/client/ClientUtil.java