Fix next/server being required during build (#39310)

packages/next/server.js

@@ -1,4 +1,4 @@
-module.exports = {
+const serverExports = {
   NextRequest: require('next/dist/server/web/spec-extension/request')
     .NextRequest,
   NextResponse: require('next/dist/server/web/spec-extension/response')
@@ -7,6 +7,11 @@ module.exports = {
     .userAgentFromString,
   userAgent: require('next/dist/server/web/spec-extension/user-agent')
     .userAgent,
-  // eslint-disable-next-line no-undef
-  URLPattern: URLPattern,
 }
+
+if (typeof URLPattern !== 'undefined') {
+  // eslint-disable-next-line no-undef
+  serverExports.URLPattern = URLPattern
+}
+
+module.exports = serverExports

test/unit/web-runtime/next-server-node.test.ts

@@ -0,0 +1,5 @@
+import 'next/dist/server/node-polyfill-fetch'
+
+it('should be able to require next/server outside edge', () => {
+  require('next/server')
+})