function packUiEsm(cb) {
    src(`${feModuleSrc}/ui.js`)
        .pipe(gulpEsbuild({
            outfile: 'ui.esm.js',
            bundle: true,
            format: 'esm',
            platform: 'browser',
            minify: false,
            sourcemap: false,
            target: [
                'es2020',
            ],
        }))
        .on('error', function(err) {
            console.error('[packUiEsm] ERROR ', err)
            cb(err)
        })
        .pipe(greplace(/version = "(.*)-src"/, 'version = "$1-esm"'))
        .pipe(dest(feDest))
        .on('end', function() {
            // in case of success
            cb()
        })
}
ESBuild ui.js as ES Module (not minified)
@param {Function} cb Callback