第二个sass输出目录中的Ionic css文件为空

我尝试将第二个sass“周期”添加到我的ionic项目中。以下是mygulpfile.js的相关部分

var paths = {
  sass: ['./scss/**/*.scss'],
  themesass: ['./www/data/theme/css/**/*.scss']
};

gulp.task('default', ['sass','themesass']);

gulp.task('sass', function(done) {
  gulp.src('./scss/ionic.app.scss')
    .pipe(sass())
    .on('error', sass.logError)
    .pipe(gulp.dest('./www/css/'))
    .pipe(minifyCss({
      keepSpecialComments: 0
    }))
    .pipe(rename({ extname: '.min.css' }))
    .pipe(gulp.dest('./www/css/'))
    .on('end', done);
});

gulp.task('themesass', function(done) {
  gulp.src('./www/data/theme/css/style.scss')
    .pipe(sass())
    .on('error', sass.logError)
    .pipe(gulp.dest('./www/data/theme/css/'))
    .pipe(minifyCss({
      keepSpecialComments: 0
    }))
    .pipe(rename({ extname: '.min.css' }))
    .pipe(gulp.dest('./www/data/theme/css/'))
    .on('end', done);
});

gulp.task('watch', function() {
  gulp.watch(paths.sass, ['sass']);
  gulp.watch(paths.themesass, ['themesass']);
});

更改style.css时，我在终端中得到以下输出：

File changed: www/data/theme/css/style.scss
[12:07:03] Starting 'themesass'...
[12:07:03] Finished 'themesass' after 14 ms
CSS changed:  www/data/theme/css/style.css
CSS changed:  www/data/theme/css/style.min.css

不过，这两个文件（style.css和style.min.css）都保持为空。我错过了什么