{"ast_node_type":"other","tokens":[{"end":57,"kind":"keyword","start":0,"text":"//"}]}
            // FIXME(#120456) - is `swap_remove` correct?
            debug_assert!(enclosing_breakables.stack.len() == index + 1);
            enclosing_breakables.by_id.swap_remove(&id).expect("missing breakable context");