NuPlayerRenderer: Handle AMessage post error in openAudioSink

AMessage::postAndAwaitResponse can fail if the target looper no
longer exists or if allocation of the reply token fails. Check for
error in these cases to avoid deferencing a NULL response.
Test: compiles
Bug: 34805421

(cherry picked from commit b90c8f42036ea773e938cadd0d52480ac703edd7)

Change-Id: Ib76c111a39462e867a41f320c0ba0a220a0c5641
diff --git a/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.cpp b/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.cpp
index 42e95da..9350440 100644
--- a/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.cpp
+++ b/media/libmediaplayerservice/nuplayer/NuPlayerRenderer.cpp
@@ -405,10 +405,10 @@
     msg->setInt32("flags", flags);
 
     sp<AMessage> response;
-    msg->postAndAwaitResponse(&response);
+    status_t postStatus = msg->postAndAwaitResponse(&response);
 
     int32_t err;
-    if (!response->findInt32("err", &err)) {
+    if (postStatus != OK || response.get() == nullptr || !response->findInt32("err", &err)) {
         err = INVALID_OPERATION;
     } else if (err == OK && isOffloaded != NULL) {
         int32_t offload;