StreamPipeToState::doWrite needs to handle a null write promise

rdar://164088592
https://bugs.webkit.org/show_bug.cgi?id=302067

Reviewed by Chris Dumez.

In case of a worker, the write operation may result in an exception, leading to a null promise.
In that case, we bail out.

* Source/WebCore/Modules/streams/StreamPipeToUtilities.cpp:
(WebCore::StreamPipeToState::doWrite):

Canonical link: https://commits.webkit.org/302645@main

Author: youennf

Source/WebCore/Modules/streams/StreamPipeToUtilities.cpp

@@ -322,6 +322,9 @@ void StreamPipeToState::doWrite(JSC::JSValue value)
 
     m_pendingReadRequest = nullptr;
     m_pendingWritePromise = writableStreamDefaultWriterWrite(m_writer, value);
+    if (!m_pendingWritePromise)
+        return;
+
     RefPtr { m_pendingWritePromise }->markAsHandled();
 
     loop();