Impossible to invoke a method ("url") on a null variable.
<div class="artiste-block">
<ul class="list-unstyled badge-list">
{% for pressLink in pressLinks %}
<li><a class="badge badge-xl rounded-pill" href="{{ pressLink.press_url() }}" target="_blank">{{ pressLink.press_text() }}</a></li>
{% endfor %}
{% for pdfLink in pdfLinks %}
<li><a class="badge badge-xl rounded-pill" href="{{ pdfLink.pdf_content().toFile().url() }}" target="_blank">{{ pdfLink.pdf_text() }}</a></li>
{% endfor %}
</ul>
</div>
{% endif %}
</div>
<div class="artiste-block">