fix(preview-server): typescript automatically being installed (#2677)

Author: gabrielmfern

.changeset/tricky-meals-hope.md

@@ -0,0 +1,5 @@
+---
+"@react-email/preview-server": patch
+---
+
+fix unwanted dependency installation when typescript's not installed

packages/preview-server/next.config.ts renamed to packages/preview-server/next.config.mjs

@@ -1,6 +1,7 @@
-import type { NextConfig } from 'next';
-
-const nextConfig: NextConfig = {
+/**
+ * @type {import('next').NextConfig}
+ */
+const nextConfig = {
   serverExternalPackages: ['esbuild'],
   // Noticed an issue with typescript transpilation when going from Next 14.1.1 to 14.1.2
   // and I narrowed that down into this PR https://github.com/vercel/next.js/pull/62005

packages/preview-server/tsconfig.json

@@ -40,7 +40,8 @@
     "**/*.ts",
     "**/*.tsx",
     ".next/types/**/*.ts",
-    ".next/dev/types/**/*.ts"
+    ".next/dev/types/**/*.ts",
+    "next.config.mjs"
   ],
   "exclude": [".next", "dist", "node_modules"]
 }

packages/react-email/src/commands/build.ts

@@ -76,11 +76,11 @@ const setNextEnvironmentVariablesForBuild = async (
   builtPreviewAppPath: string,
 ) => {
   const nextConfigContents = `
-const path = require('path');
+import path from 'path';
 const emailsDirRelativePath = path.normalize('${emailsDirRelativePath}');
 const userProjectLocation = '${process.cwd().replace(/\\/g, '/')}';
 /** @type {import('next').NextConfig} */
-module.exports = {
+const nextConfig = {
   env: {
     NEXT_PUBLIC_IS_BUILDING: 'true',
     EMAILS_DIR_RELATIVE_PATH: emailsDirRelativePath,
@@ -95,12 +95,12 @@ module.exports = {
   experimental: {
     webpackBuildWorker: true
   },
-}`;
+}
 
-  await fs.promises.rm(path.resolve(builtPreviewAppPath, './next.config.ts'));
+export default nextConfig`;
 
   await fs.promises.writeFile(
-    path.resolve(builtPreviewAppPath, './next.config.js'),
+    path.resolve(builtPreviewAppPath, './next.config.mjs'),
     nextConfigContents,
     'utf8',
   );