{"ast_node_type":"variable","tokens":[{"end":86,"kind":"keyword","start":0,"text":"if"}]}
                if let Ok(arg) = ecx.source_map().span_to_snippet(captured_arg_span) {
                    fmt_span.from_inner(InnerSpan::new(err.span.start, err.span.end));
                    let span = match args.unnamed_args().last() {