gulp使用了gulp-minify-css会报错?

Question

这是编译sass的代码:

function sass() {

  return gulp.src(['src/scss/{app,mall,datetime-picker,foundation-datepicker,style}.scss'])

    .pipe($.sourcemaps.init())

    .pipe($.sass({

      includePaths: PATHS.sass

    })

      .on('error', $.sass.logError))

    .pipe($.autoprefixer({

      browsers: COMPATIBILITY

    }))

    // Comment in the pipe below to run UnCSS in production

    //.pipe($.if(PRODUCTION, $.uncss(UNCSS_OPTIONS)))

    .pipe($.if(PRODUCTION, $.cssnano()))

    .pipe($.if(!PRODUCTION, $.sourcemaps.write()))

    .pipe($.minifyCss())

    .pipe(gulp.dest(PATHS.dist))

    .pipe(browser.reload({ stream: true }));

}

没加.pipe($.minifyCss())的时候没报错