fix: correctly find site root when using SSR with Nx (#1281)

* fix: conditionally change working directory

* feat: add ssr route for testing

Author: orinokai

demos/nx-next-monorepo-demo/apps/demo-monorepo/pages/api/index.js

@@ -0,0 +1,7 @@
+// Next.js API route support: https://nextjs.org/docs/api-routes/introduction
+
+export default function handler(req, res) {
+  res.status(200).json({
+    body: 'Hello world',
+  });
+}

src/templates/getHandler.ts

@@ -27,10 +27,12 @@ type Mutable<T> = {
 // We return a function and then call `toString()` on it to serialise it as the launcher function
 // eslint-disable-next-line max-params
 const makeHandler = (conf: NextConfig, app, pageRoot, staticManifest: Array<[string, string]> = [], mode = 'ssr') => {
-  // Change working directory into the site root
+  // Change working directory into the site root, unless using Nx, which moves the
+  // dist directory and handles this itself
   const dir = path.resolve(__dirname, app)
-
-  process.chdir(dir)
+  if (pageRoot.startsWith(dir)) {
+    process.chdir(dir)
+  }
 
   // This is just so nft knows about the page entrypoints. It's not actually used
   try {