ArViz: Fix compile error

Signed-off-by: Fabian Paus <fabian.paus@kit.edu>

source/RobotAPI/components/ArViz/Client/Client.h

@@ -107,7 +107,7 @@ namespace viz
         {
             std::vector<viz::Layer> layers;
             viz::Layer& newLayer = layers.emplace_back(this->layer(name));
-            if (element != nullptr)
+            if (element)
             {
                 newLayer.add(element);
             }