Check if 'formatAmpMessages' returns a none empty string in Next.js b…

…uild process
vercel · Oct 23, 2019 · c37ba81 · c37ba81
1 parent 1ff5005
commit c37ba81
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/packages/next/build/output/index.ts b/packages/next/build/output/index.ts
@@ -173,7 +173,7 @@ buildStore.subscribe(state => {
       }
 
       if (Object.keys(amp).length > 0) {
-        warnings = (warnings || []).concat(formatAmpMessages(amp))
+        warnings = (warnings || []).concat(formatAmpMessages(amp) || [])
         if (!warnings.length) warnings = null
       }
     }