message: fix missing return in RaycastVolumeRenderer::renderFrame()
diff: @@ -223,7 +223,7 @@ namespace ospray {
  if (mpicommon::IamTheMaster()) {
  //NOTE: This function is for offload render worker ranks only, thus the
  // master punts to default behavior
  - Renderer::renderFrame(fb, channelFlags);
  + return Renderer::renderFrame(fb, channelFlags);
  }
  using DDBV = DataDistributedBlockedVolume;
  