fix(preview-server): default imports of node modules breaking templates (#2936)

Co-authored-by: cubic-dev-ai[bot] <191113872+cubic-dev-ai[bot]@users.noreply.github.com>

Author: gabrielmfern

.changeset/olive-walls-kiss.md

@@ -0,0 +1,5 @@
+---
+"@react-email/preview-server": patch
+---
+
+fix default imports of node modules breaking

packages/preview-server/src/utils/run-bundled-code.spec.ts

@@ -1,3 +1,4 @@
+import path from 'node:path';
 import { z } from 'zod';
 import { isErr, isOk } from './result';
 import { runBundledCode } from './run-bundled-code';
@@ -51,6 +52,24 @@ describe('runBundledCode()', () => {
     ).toEqual(42);
   });
 
+  // see https://github.com/resend/react-email/issues/2930
+  it('works when using default imports for node:path', async () => {
+    const result = await runBundledCode(
+      `
+import path from 'node:path';
+
+export default path.join('a', 'b', 'c');
+    `,
+      'test-path.js',
+    );
+    if (!isOk(result)) {
+      expect(isOk(result), 'there should be no errors').toBe(true);
+      console.log(result.error);
+      return;
+    }
+    expect(result.value).toEqual({ default: path.join('a', 'b', 'c') });
+  });
+
   it('returns an error if the code throws', async () => {
     const result = await runBundledCode(
       'throw new Error("Test error");',

packages/preview-server/src/utils/run-bundled-code.ts

@@ -117,19 +117,17 @@ export async function runBundledCode(
 
       if (m in staticNodeModulesForVM) {
         const moduleExports = staticNodeModulesForVM[m];
-        // Get all own property keys (including symbols and non-enumerable)
         const exportKeys = Reflect.ownKeys(moduleExports).filter(
           (key) => typeof key === 'string',
         ) as string[];
 
-        // Create a SyntheticModule that exports the static module
         const syntheticModule = new vm.SyntheticModule(
-          exportKeys,
+          [...exportKeys.filter((k) => k !== 'default'), 'default'],
           function () {
-            // Set all exports from the static module
             for (const key of exportKeys) {
               this.setExport(key, moduleExports[key]);
             }
+            this.setExport('default', moduleExports);
           },
           {
             context,
@@ -139,21 +137,17 @@ export async function runBundledCode(
         return syntheticModule;
       }
 
-      // For external modules, import them and create a SyntheticModule
       const importedModule = await import(specifier, {
         with: extra.attributes as ImportAttributes,
       });
 
-      // Get all own property keys (including symbols and non-enumerable)
-      // Filter to only string keys as SyntheticModule only supports string export names
       const exportKeys = Reflect.ownKeys(importedModule).filter(
         (key) => typeof key === 'string',
       ) as string[];
 
       const syntheticModule = new vm.SyntheticModule(
         exportKeys,
         function () {
-          // Set all exports from the imported module
           for (const key of exportKeys) {
             this.setExport(key, importedModule[key]);
           }