I want to write a visual plugin. I started by writing a visual plugin that is only supposed to draw a line at the same position with every ~/pose/local/info message. I attached the plugin to a SDF description of a robot. So I launch the gazebo by the $ gazebo command and then include the robot from the left side menu. The simulation runs as normal before I put the robot in. Then it shuts down without error. Why and how can I fix it?

source code of the plugin:

#include "VisualizationPlugin.hh"

namespace gazebo
{
    namespace rendering
    {

        // Constructor
        VisualizationPlugin::VisualizationPlugin()
        {}

        // Destructor
        VisualizationPlugin::~VisualizationPlugin()
        {}

        // Load the plugin
        void VisualizationPlugin::Load( VisualPtr _parent, sdf::ElementPtr _sdf )
        {
            this->visual = _parent;

            this->visualNamespace = "visual/";

            this->node = gazebo::transport::NodePtr(new gazebo::transport::Node());
            this->node->Init();

            this->sub = this->node->Subscribe("~/pose/local/info", &VisualizationPlugin::Visualize, this);

        }

        void VisualizationPlugin::Visualize(ConstPosesStampedPtr &msg)
        {
            this->line = this->visual->CreateDynamicLine(RENDERING_LINE_STRIP);

            this->line->AddPoint( math::Vector3( 0, 0, 0 ), common::Color::White );
            this->line->AddPoint( math::Vector3( 1, 1, 1 ), common::Color::White );
            this->line->setVisibilityFlags(GZ_VISIBILITY_GUI);
            this->visual->SetVisible(true);
        }

    }
}