Sometimes I get this annoying problem and I have no idea what causes it.
Form the base template file (partials/base.html.twig), I set the global variable for site and theme's configuration.
TWIG
{% set theme_config = attribute(config.themes, config.system.pages.theme) %}
<!DOCTYPE html>
<html lang="{{ grav.language.getLanguage ?: 'en' }}">
<head>
{% include "partials/head.html.twig" %}
</head>
<body>
{% block content %},{% endblock %}
</body>
</html>
Here is my modular.html.twig:
TWIG
{% extends 'partials/base.html.twig' %}
{% block content %}
{% for module in page.collection() %}
{# theme_config is still available here #}
{{ module.content }}
{% endfor %}
{% endblock %}
In my modular page themeconfig variable is null. However I still can get config variable of Grav. This problem sometimes happens, sometimes not. My only solution right now is re-set themeconfig variable in each modular page:
TWIG
{% set theme_config = attribute(config.themes, config.system.pages.theme) %}
If you have any idea of why this happens, please let me know. Thanks!