fix js logic and decouple it from the font logic

templates/gulpfile.js.twig

@@ -38,8 +38,12 @@ gulp.task('fonts-{{ package.name }}', function() {
 // Provide fonts from all libraries
 gulp.task('fonts', {% if fontDefined %}gulp.series(gulp.parallel({% for name, package in bower_assets %}{% if package.fonts is defined %}'fonts-{{ package.name }}', {% endif %}{% endfor %})){% endif %});
 
+{# This variable is needed to search for defined js in packages #}
+{% set jsDefined = false %}
+
 {% for name, package in bower_assets %}
 {% if package.js is defined %}
+{% set jsDefined = true %}
 // Provide JS from {{ name }}
 gulp.task('js-{{ package.name }}', function() {
   return gulp.src('{{ package.js.relative }}/**')
@@ -49,7 +53,7 @@ gulp.task('js-{{ package.name }}', function() {
 {% endif %}
 {% endfor %}
 // Provide JS from all libraries
-gulp.task('js', {% if fontDefined %}gulp.series(gulp.parallel({% for name, package in bower_assets %}{% if package.js is defined %}'js-{{ package.name }}', {% endif %}{% endfor %})){% endif %});
+gulp.task('js', {% if jsDefined %}gulp.series(gulp.parallel({% for name, package in bower_assets %}{% if package.js is defined %}'js-{{ package.name }}', {% endif %}{% endfor %})){% endif %});
 
 // Pre-process CSS
 gulp.task('css', function() {