wp-includes/html-api/class-wp-html-processor.php:653Returns context for why the parser aborted due to unsupported HTML, if it did.
WP_HTML_Unsupported_Exception|null public function get_unsupported_exception() { return $this->unsupported_exception; }Introduced in 6.7.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/html-api/class-wp-html-processor.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.