audio frame resizer: avoid dropping valid frames

Change-Id: I456c6cbe5ec12055902647ac43d416e83b93e8d2
Reviewed-by: Philippe Gorley <philippe.gorley@savoirfairelinux.com>

src/media/audio/audio_frame_resizer.cpp

@@ -96,9 +96,8 @@ AudioFrameResizer::enqueue(std::shared_ptr<AudioFrame>&& frame)
     }
 
     auto nb_samples = samples();
-    if (nb_samples == 0 && f->nb_samples == frameSize_) {
+    if (cb_ && nb_samples == 0 && f->nb_samples == frameSize_) {
         nextOutputPts_ = frame->pointer()->pts + frameSize_;
-        if (cb_)
         cb_(std::move(frame));
         return; // return if frame was just passed through
     }