将nodemon与gulp一起使用不起作用

Question

我使用gulp和broswersync来观察任何前端变化。但同时我正在使用node.js所以如果我在服务器端更改了任何内容，我需要nodemon重启服务器。不确定我做得对，下面是我的gulpfile.js

var gulp = require('gulp');
    var sass = require('gulp-sass');
    var browserSync = require('browser-sync').create();
    var reload      = browserSync.reload;
    var nodemon = require('gulp-nodemon');

    gulp.task('serve', function() {

        browserSync.init({
            server: "./public"
        });

        gulp.watch(['./public/*.html', './public/js/*.js']).on('change', reload);
    });

    gulp.task('sass', function () {
      return gulp.src('./public/sass/**/*.scss')
        .pipe(sass().on('error', sass.logError))
        .pipe(gulp.dest('./public/css'))
        .pipe(reload({stream: true}));
    });

    gulp.task('sass:watch', function () {
      gulp.watch('./public/sass/**/*.scss', ['sass'])
    });

    // our gulp-nodemon task
    gulp.task('nodemon', function (cb) {
        var started = false;
        return nodemon({
            script: './bin/www',
            ext: 'js',
            ignore: ['public/*'],
            env: {
                'NODE_ENV': 'development',
                'DEBUG': 'appname:*'
         }
        }).on('start', function () {
            if (!started) {
                cb();
                started = true;
            }
        })
        .on('crash', function() {
            console.log('nodemon.crash');
        })
        .on('restart', function() {
            console.log('nodemon.restart');
        })
        .once('quit', function () {
            process.exit();
        });
    });

    gulp.task('default', ['serve','sass','sass:watch','nodemon']);

我运行gulp，但错误

Error: listen EADDRINUSE :::3000