Issue #3293294 by sdstyles: Fix warning: Array to string conversion in...

{% if attributes.id|default %}

  {% set heading_id = attributes.id|clean_class|replace({'_': '-'}) ~ '-heading' %}

{% else %}

  {% set heading_id = 'heading-' ~ heading|clean_class|replace({'_': '-'}) ~ '-' ~ ("now"|date("Ydm")) %}

  {% set heading_markup = heading['#markup'] ?: heading %}

  {% set heading_id = 'heading-' ~ heading_markup|clean_class|replace({'_': '-'}) ~ '-' ~ ("now"|date("Ydm")) %}

{% endif %}

{# Always use a descriptive label (block description) for your block