message: throw a proper std::runtime_error when Embree can't be initialized
diff: @@ -75,6 +75,8 @@ namespace ospray {
  {
  Device::commit();
  + TiledLoadBalancer::instance = make_unique<LocalTiledLoadBalancer>();
  +
  if (!embreeDevice) {
  // -------------------------------------------------------
  // initialize embree. (we need to do this here rather than in
  @@ -87,11 +89,9 @@ namespace ospray {
  if (erc != RTC_ERROR_NONE) {
  // why did the error function not get called !?
  postStatusMsg() << "#osp:init: embree internal error number " << erc;
  - assert(erc == RTC_ERROR_NONE);
  + throw std::runtime_error("failed to initialize Embree");
  }
  }
  -
  - TiledLoadBalancer::instance = make_unique<LocalTiledLoadBalancer>();
  }
  ///////////////////////////////////////////////////////////////////////////
  