{"ast_node_type":"variable","tokens":[{"end":98,"kind":"keyword","start":0,"text":"let"}]}
            let block = self.mk_block(thin_vec![], BlockCheckMode::Default, self.prev_token.span);
            let err_expr = self.mk_expr(expr.span, ExprKind::Err(guar));
            return Ok(self.mk_expr(