fix a lint issue

Author: lukesandberg

packages/next/errors.json

@@ -824,5 +824,6 @@
   "823": "Timeout waiting for error state from frontend. The browser may not be responding to HMR messages.",
   "824": "URL is required in MCP browser response. This is a bug in Next.js.",
   "825": "Timeout waiting for response from frontend. The browser may not be responding to HMR messages.",
-  "826": "unknown bundler: %s"
+  "826": "unknown bundler: %s",
+  "827": "Pass either `webpack` or `turbopack`, not both."
 }

packages/next/src/server/next.ts

@@ -542,10 +542,10 @@ function createServer(
     (options.turbo || options.turbopack || process.env.IS_TURBOPACK_TEST)
   ) {
     if (options.webpack) {
-      throw new Error('Pass either webpack or turbopack, not both.')
+      throw new Error('Pass either `webpack` or `turbopack`, not both.')
     }
     process.env.TURBOPACK = '1'
-  } else if (!options.webpack) {
+  } else if (!options?.webpack) {
     // If no options are set we default to turbopack
     process.env.TURBOPACK = 'auto'
   }