The solution for this was explained to me on another forum - it turns out that I was using a non system font - if you change that the error will go away!
I’m no expert, but it seems as if the system is trying to find a font that doesn’t have an alternative format (ie bold, semibold etc)
Either change your font to a system font (you can do this in your theme editor, system fonts appear at the top of the typography section) or you’ll have to find a code which will replace a non-existent font face with one that already exists.
This problem can be related with wrong font variable name. Please check if the font variable name is the same in theme.liquid and settings_schema.json.
For some reason this line
{%- assign base_font_bold = base_font | font_modify: ‘weight’, ‘bold’ -%}
returns a null value for base_font_bold. That causes an error here:
After that, I checked the website and I see that the fonts are not equal so I edited the theme.css.liquid file.
For some reason, some OOTB code from my theme wasn’t working nicely. I found the right code and paste it on all places where the font-family was mentioned.
/* custom added to change all fonts to be the same */
font-family: {% if fnt_df_bd == ‘1’ %}{{font-stack-body}}{% elsif fnt_df_bd == ‘2’ %}{{font-stack-heading}}{% else %}{{font-stack-sub}}{% endif %};