message: fix crash in videowidget
diff: @@ -50,6 +50,10 @@ struct VideoWidget::SoundContext {
  snd = dev.load(std::unique_ptr<VideoWidget::Sound>(new VideoWidget::Sound(*this,sampleRate,isMono)));
  }
  + ~SoundContext() {
  + snd = SoundEffect();
  + }
  +
  void pushSamples(const std::vector<float>& s) {
  std::lock_guard<std::mutex> guard(syncSamples);
  size_t sz = samples.size();
  