Editor: Add further test coverage for wp_render_elements_support().

Props dmsnell, aaronrobertshaw.
Fixes #59578.


git-svn-id: https://develop.svn.wordpress.org/trunk@56828 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/block-supports/elements.php

@@ -36,6 +36,9 @@ function wp_render_elements_support( $block_content, $block ) {
 	}
 
 	$block_type = WP_Block_Type_Registry::get_instance()->get_registered( $block['blockName'] );
+	if ( ! $block_type ) {
+		return $block_content;
+	}
 
 	$element_color_properties = array(
 		'button'  => array(