What is a crucial intermediate step when extending a theme using a themelet?

Choosing 'Themelet' as the theme asset to extend is a crucial intermediate step when extending a theme using a themelet. In Liferay, a themelet allows developers to customize or enhance existing themes without having to create a completely new one from scratch. By selecting 'Themelet' as the asset to extend, you are specifically indicating your intention to build upon an existing theme’s structure and functionality.

This choice ensures that the framework recognizes your new themelet as part of the overall theming strategy, integrating it properly into the Liferay ecosystem. It allows for the inheritance of styles and templates, facilitating efficient customization while maintaining consistency with the original theme’s aesthetic attributes.

Other actions like running npm install or editing source files are important in their own right but do not initiate the process of extending a themelet. Listing variables in a config file could pertain to custom settings for themes but is not as foundational to the initial step of starting an extension based on an existing theme. Thus, selecting 'Themelet' is the essential first step in this process.