Fallback to react-dom/server.browser in Pages router if Edge version is not available

`react-dom/server.edge` is not available in React 18.
We were using `.browser` before when we were on React 18 so this should be safe.

Author: eps1lon

packages/next/src/build/shims/ReactDOMServerEdgeIfAvailable.d.ts

@@ -0,0 +1 @@
+export * from 'react-dom/server.edge'

packages/next/src/build/shims/ReactDOMServerEdgeIfAvailable.js

@@ -0,0 +1,18 @@
+let ReactDOMServer
+
+try {
+  ReactDOMServer = require('react-dom/server.edge')
+} catch (error) {
+  if (
+    // TODO: copilot suggestion. Does this code actually exist?
+    error.code !== 'MODULE_NOT_FOUND' &&
+    // TODO: actually encountered that
+    error.code !== 'ERR_PACKAGE_PATH_NOT_EXPORTED'
+  ) {
+    throw error
+  }
+  // TOOD: Ensure App Router does not bundle this
+  ReactDOMServer = require('react-dom/server.browser')
+}
+
+module.exports = ReactDOMServer

packages/next/src/server/render.tsx

@@ -40,7 +40,7 @@ import type { Revalidate, SwrDelta } from './lib/revalidate'
 import type { COMPILER_NAMES } from '../shared/lib/constants'
 
 import React, { type JSX } from 'react'
-import ReactDOMServerEdge from 'react-dom/server.edge'
+import ReactDOMServerEdge from '../build/shims/ReactDOMServerEdgeIfAvailable'
 import { StyleRegistry, createStyleRegistry } from 'styled-jsx'
 import {
   GSP_NO_RETURNED_VALUE,

packages/next/webpack.config.js

@@ -13,6 +13,7 @@ const pagesExternals = [
   'react-dom/package.json',
   'react-dom/client',
   'react-dom/server',
+  'react-dom/server.browser',
   'react-dom/server.edge',
   'react-server-dom-webpack/client',
   'react-server-dom-webpack/client.edge',