feat: Only emit __esModule properties in CJS modules when there is a default export

Author: lforst

dev-packages/rollup-utils/npmHelpers.mjs

@@ -56,9 +56,8 @@ export function makeBaseNPMConfig(options = {}) {
 
       sourcemap: true,
 
-      // Include __esModule property when generating exports
-      // Before the upgrade to Rollup 4 this was included by default and when it was gone it broke tests
-      esModule: true,
+      // Include __esModule property when there is a default prop
+      esModule: 'if-default-prop',
 
       // output individual files rather than one big bundle
       preserveModules: true,