check return value

vercel · Mar 10, 2022 · a28c30f · a28c30f
1 parent 6cb26b9
commit a28c30f
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/packages/next/server/web/sandbox/readable-stream.ts b/packages/next/server/web/sandbox/readable-stream.ts
@@ -68,7 +68,7 @@ class ReadableStream<T> {
     }
 
     const started = opts.start && opts.start(controller)
-    if (typeof started.then === 'function') {
+    if (started && typeof started.then === 'function') {
       started.then(() => registerPull())
     } else {
       registerPull()