Gulp停留在“开始'ass'...”

Question

我无法正常使用 gulp手表。当我运行它时，它成功地将CSS输出到/ css文件夹，但是随后挂起，没有经过“ sass”步骤。我的gulpfile出问题了吗？

gulpfile.js

    var gulp = require('gulp'),
    livereload = require('gulp-livereload'),
    gulpIf = require('gulp-if'),
    sass = require('gulp-sass'),
    autoprefixer = require('gulp-autoprefixer'),
    sourcemaps = require('gulp-sourcemaps');

gulp.task('sass', function () {
  gulp.src('./sass/**/*.scss')
    .pipe(sourcemaps.init())
        .pipe(sass({outputStyle: 'compressed'}).on('error', sass.logError))
        .pipe(autoprefixer('last 2 version'))
    .pipe(sourcemaps.write('./'))
    .pipe(gulp.dest('./css'));
});

gulp.task('watch', function(){
    livereload.listen();

    gulp.watch('./sass/**/*.scss', gulp.series('sass'));
    gulp.watch(['./css/style.css', './**/*.html.twig', './js/*.js'], function (files){
        livereload.changed(files)
    });
});

终端输出：

[13:53:47] Using gulpfile ~/Documents/Jurassic/project/drupal/web/themes/custom/nekken/gulpfile.js
[13:53:47] Starting 'watch'...
[13:53:54] Starting 'sass'...