Symfony flash for Pixeladmin JS alerts

{% if app.session.flashbag.peekAll|length > 0 %}

    {% set flashbag = app.session.flashbag.all %}
    <script>
        init.push(function () {
            {% for type,messages in flashbag %}
            {% for message in messages %}

            PixelAdmin.plugins.alerts.add('<strong>{{ message[0]|trans }}</strong> {{ message[1]|trans(message[2], 'backend')|raw }}', {
                type: '{{ type }}',
                namespace: 'pa_page_alerts_dark',
                {% if message[3] is not null %}
                'auto_close': {{ message[3] }},
                {% endif %}
                classes: 'alert-dark'
            });

            {% endfor %}
            {% endfor %}
        });
    </script>

{% endif %}