Say you have a textarea field -- it's not being trimmed and whitespace-only is a valid value. Maybe you're letting users write and save whitespace code or something.

When rendering a text area with only whitespace as a value, it will disappear. the {% spaceless %} block strips it out.

This doesn't seem correct: if whitespace-only is a valid value, the form component and twig bridge shouldn't mess with it.

Work around: use a custom form theme without spaceless. This could also be the fix for this issue.

{# in some twig template #}

{% form_theme someVariableWithAFormView _self %}

{% block textarea_widget %}
<textarea {{ block('widget_attributes') }}>{{ value }}</textarea>
{% endblock textarea_widget %}