Widget Screen Documentation for Fallbacks and Default widgets

[DaisyOlsen]

Feedback from WPTavern:
One less-obvious piece of documentation should center on how to handle fallbacks or default widgets. Traditionally, themes that needed to show a default set of widgets would check if the sidebar has widgets and fall back to using the_widget() to output one or more defaults. While theme authors can still do that, we should start to transition them across the board to the block system.

[noisysocks]

Here is where this pattern is documented:

https://developer.wordpress.org/themes/basics/conditional-tags/#variable-sidebar-content

Something like this should work as a block-based alternative:

if ( is_active_sidebar( 'my_sidebar' ) ) {
	dynamic_sidebar( 'my_sidebar' );
} else {
	echo do_blocks( '<!-- wp:paragraph --><p>Fallback block content goes here.</p><!-- /wp:paragraph -->' );
}

[ryanwelcher]

@DaisyOlsen is this still actionable?

[DaisyOlsen]

Maybe ask @justintadlock since it was pulled directly from his feedback.

[justintadlock]

This ticket should be moved here: https://github.com/WordPress/Documentation-Issue-Tracker/issues

The code from @noisysocks looks like a good solution, but it should be shown here in the current handbook: https://developer.wordpress.org/themes/functionality/sidebars/#display-default-widgets