message: fix a potential crasher when copying the camera stream
  there was a very small race, where we would dereference a pointer
  that might not be set yet.
diff: @@ -1451,8 +1451,16 @@ void OpenGLDriver::updateStreams(driver::DriverApi* driver) {
  if (UTILS_UNLIKELY(!mExternalStreams.empty())) {
  OpenGLBlitter::State state;
  for (GLTexture* t : mExternalStreams) {
  - assert(t && t->hwStream);
  - if (!static_cast<GLStream*>(t->hwStream)->isNativeStream()) {
  + assert(t);
  +
  + GLStream* s = static_cast<GLStream*>(t->hwStream);
  + if (UTILS_UNLIKELY(s == nullptr)) {
  + // this can happen because we're called synchronously and the setExternalStream()
  + // call may bot have been processed yet.
  + continue;
  + }
  +
  + if (!s->isNativeStream()) {
  state.setup();
  updateStream(t, driver);
  }
  @@ -2253,14 +2261,12 @@ void OpenGLDriver::setViewportScissor(
  #define DEBUG_NO_EXTERNAL_STREAM_COPY false
  void OpenGLDriver::updateStream(GLTexture* t, driver::DriverApi* driver) noexcept {
  + SYSTRACE_CALL();
  +
  GLStream* s = static_cast<GLStream*>(t->hwStream);
  - if (UTILS_UNLIKELY(s == nullptr)) {
  - // this can happen because we're called synchronously and the setExternalStream() call
  - // may bot have been processed yet.
  - return;
  - }
  + assert(s);
  + assert(!s->isNativeStream());
  - if (UTILS_LIKELY(!s->isNativeStream())) {
  // round-robin to the next texture name
  if (UTILS_UNLIKELY(DEBUG_NO_EXTERNAL_STREAM_COPY ||
  bugs.disable_shared_context_draws || !mOpenGLBlitter)) {
  @@ -2293,8 +2299,7 @@ void OpenGLDriver::updateStream(GLTexture* t, driver::DriverApi* driver) noexcep
  info.height = s->height;
  Platform::ExternalTexture* ets = s->user_thread.infos[s->user_thread.cur].ets;
  - mPlatform.reallocateExternalStorage(ets, info.width, info.height,
  - TextureFormat::RGB8);
  + mPlatform.reallocateExternalStorage(ets, info.width, info.height, TextureFormat::RGB8);
  glActiveTexture(GL_TEXTURE0);
  glBindTexture(GL_TEXTURE_2D, writeTexture);
  @@ -2347,7 +2352,6 @@ void OpenGLDriver::updateStream(GLTexture* t, driver::DriverApi* driver) noexcep
  });
  }
  }
  -}
  void OpenGLDriver::readStreamPixels(Driver::StreamHandle sh,
  uint32_t x, uint32_t y, uint32_t width, uint32_t height,
  