{"ast_node_type":"variable","tokens":[{"end":42,"kind":"keyword","start":0,"text":"let"}]}
                    let (Ok(e) | Err(e)) =
                let guar = hidden_ty.ty.error_reported().err().unwrap_or_else(|| {
                        prev.build_mismatch_error(&hidden_ty, self.tcx).map(|d| d.emit());