Gulp: AssertionError: Task never defined: [object Object]

[lgg]

$ gulp -v
[08:52:07] Requiring external module babel-register
[08:52:07] CLI version 1.2.2
[08:52:07] Local version 4.0.0-alpha.2

error:

...
at Object.<anonymous> (build.js:9:20)
...

line 9:
const build = gulp.series(buildJs, buildPug);

build.js:

'use strict';

import gulp from 'gulp';
import buildJs from './js'
import buildPug from './pug'

const build = gulp.series(buildJs, buildPug);

gulp.task('build', build);
export { build };

js.js:

'use strict';

import gulp from 'gulp'
import babel from 'gulp-babel'
import webpack from  'webpack-stream'
import concat from 'gulp-concat'
import uglify from 'gulp-uglify'
import plumber from 'gulp-plumber'
import { src, names, dest } from '../paths'


/* -------------------- JS */
//Reload
function reloadJs() {
    return gulp.src(src.js)
        .pipe(plumber())
        //.pipe(concat(names.js))
        .pipe(babel({
            presets: ['es2015']
        }))
        .pipe(webpack( require('../webpack.config.js') ))
        .pipe(gulp.dest(dest.js))
}

//Build
function buildJs() {
    return gulp.src(src.js)
        .pipe(plumber())
        //.pipe(concat(names.js))
        .pipe(babel({
            presets: ['es2015']
        }))
        .pipe(webpack( require('../webpack.config.js') ))
        .pipe(uglify())
        .pipe(gulp.dest(dest.js))
}

export { buildJs, reloadJs };

pug.js:

'use strict';

import gulp from 'gulp';
import pug from 'gulp-pug';
import plumber from 'gulp-plumber';
import notify from 'gulp-notify';
import { src, names, dest } from '../paths'
import { config } from '../config'


/* -------------------- PugJs */
//Reload
function reloadPug() {
    return gulp.src(src.pug)
        .pipe(plumber())
        .pipe(pug({
            locals: config.pug.locals,
            pretty: true
        }))
        .pipe(gulp.dest(dest.html))
}

//Build
function buildPug() {
    return gulp.src(src.pug)
        .pipe(plumber())
        .pipe(pug({
            locals: config.pug.locals
        }))
        .pipe(notify(config.msg.build.pug))
        .pipe(gulp.dest(dest.html))
}


export { buildPug, reloadPug };

Nobody answered the same question on SO

[lgg]

_repo removed_

[lgg]

Even if i change build.js in that repo to:

import gulp from 'gulp';
import babel from 'gulp-babel';
import pug from 'gulp-pug';

const paths = {
    pug: {
        src: './sources/html/**/*.pug',
        dest: './dist/'
    }
};

export function buildPug() {
    return gulp.src(paths.pug.src)
        .pipe(pug({
            locals: {}
        }))
        .pipe(gulp.dest(paths.pug.dest))
}

export function watch() {
    gulp.watch(paths.pug.src, buildPug);
}

const build = gulp.series(buildPug);
export { build };

/*
 * Export a default task
 */
export default build;

it doesnt' work:

$ gulp
[09:49:09] Requiring external module babel-register
[09:49:10] Using gulpfile D:\Development\Projects\gulp-issue-1767\gulpfile.babel
.js
[09:49:10] Task never defined: default
[09:49:10] To list available tasks, try running: gulp --tasks

[phated]

Your gulpfile doesn't export anything; it only imports. The imports shorthands only work in the gulpfile, not throughout the runtime. Sorry no one answered your StackOverflow question, but this is not a support forum.