message: reset symbolRegistry if an object wasn't created (module may be loaded later)
diff: @@ -118,11 +118,14 @@ namespace ospray {
  auto *object = symbolRegistry[type] ? (*symbolRegistry[type])() : nullptr;
  // Denote the subclass type in the ManagedObject base class.
  - if (object) object->managedObjectType = OSP_TYPE;
  -
  - if (!object)
  + if (object) {
  + object->managedObjectType = OSP_TYPE;
  + }
  + else {
  + symbolRegistry.erase(type);
  throw std::runtime_error("Could not find object of type: "
  + type + ". Make sure you have the correct OSPRay libraries linked.");
  + }
  return object;
  }
  