Stylus to Alloy JMK

stylus.jmk.js

var fs = require("fs");
var path = require("path");
var util = require("util");
var styl = require("stylus");
var wrench = require("wrench");

function compileTSS(root, view) {
    var data = fs.readFileSync(path.join(root, view), "utf8"),
        tss;
    styl.render(data, function (err, css) {
        css = css.replace(/;/gi, ",");
        css = css.replace(/\}/gi, "},");
        css = css.replace(/(.+?).?\{/gi, "\"$1\": {");
        css = css.replace(/,\n\},/gi, "\n\}");
        css = css.replace(/\}\n\"/gi, "\},\n\"");
        css = css.replace(/['"]expr(.+?)['"]/gi, "expr$1");
        css = css.replace(/['"]Ti(.+?)['"]/gi, "Ti$1");
        css = css.replace(/['"]Titanium(.+?)['"]/gi, "Titanium$1");
        tss = css;
    });
    return tss;
}

task("pre:compile", function (event, logger) {
    var root = event.dir.styles;
    wrench.readdirSyncRecursive(root).forEach(function (view) {
        if (view.match("styl$")) {
            var tss = compileTSS(root, view);
            fs.writeFileSync(path.join(root, view.replace("styl", "tss")), tss);
        }
    });
});

task("post:compile", function (event, logger) {});

[ERROR] : : Cannot call method 'replace' of undefined
[ERROR] : Alloy compiler failed
になりませんか？

stylusにエラーがある場合cssが空になる。
var Log = require("log");
var log = new Log(Log.INFO);
styl.render(data, function(err, css) {
if (err)
log.error(err);