@Zens Hi, Sorry for the confusion, I thought your adding a liquid code. What are you trying to add though? A paragraph? Here is the way to show the input code. After the {% case block.type %} add the code below.
Custom liquid code I believe is a way to add a piece of a code or a snippet, not just writing a paragraph. If you wish to write a paragraph then you have to
{% when ‘custom_liquid’ %}
{{block.settings.custom_liquid}}
Regarding the error. Try removing the html block in the footer when you customize the theme. It should refresh. Let me know if you still have issues