fix: 9919 Add warning when no config is exported from next.config.js

errors/empty-configuration.md

@@ -0,0 +1,19 @@
+# Detected next.config.js, no exported configuration found
+
+#### Why This Warning Occurred
+
+There is no object exported from next.config.js or the object is empty.
+
+#### Possible Ways to Fix It
+
+Check if you export correctly configuration in next.config.js file:
+
+```
+module.exports = {
+  /* config options here */
+}
+```
+
+### Useful Links
+
+- [Introduction to next.config.js](https://nextjs.org/docs/api-reference/next.config.js/introduction)

packages/next/next-server/server/config.ts

@@ -232,7 +232,7 @@ export default function loadConfig(
     if (Object.keys(userConfig).length === 0) {
       console.warn(
         chalk.yellow.bold('Warning: ') +
-          'Detected next.config.js, no exported configuration found.'
+          'Detected next.config.js, no exported configuration found. https://err.sh/zeit/next.js/empty-configuration'
       )
     }
 

test/integration/config-empty/test/index.test.js

@@ -21,7 +21,7 @@ describe('Empty configuration', () => {
     })
     expect(stdout).toMatch(/Compiled successfully./)
     expect(stderr).toMatch(
-      /Warning: Detected next.config.js, no exported configuration found./
+      /Warning: Detected next.config.js, no exported configuration found. https:\/\/err.sh\/zeit\/next.js\/empty-configuration/
     )
   })
 
@@ -38,7 +38,7 @@ describe('Empty configuration', () => {
     await killApp(app)
 
     expect(stderr).toMatch(
-      /Warning: Detected next.config.js, no exported configuration found./
+      /Warning: Detected next.config.js, no exported configuration found. https:\/\/err.sh\/zeit\/next.js\/empty-configuration/
     )
   })
 })