fix: lazy select_with_default

nix-js/src/ir/utils.rs

@@ -121,14 +121,15 @@ pub fn downgrade_inherit(
             }
         };
         let expr = if let Some(expr) = from {
-            ctx.new_expr(
+            let select_expr = ctx.new_expr(
                 Select {
                     expr,
                     attrpath: vec![Attr::Str(ident)],
                     default: None,
                 }
                 .to_ir(),
-            )
+            );
+            ctx.new_expr(Ir::Thunk(select_expr))
         } else {
             ctx.lookup(ident)?
         };