change several functions in RobotUnitPlugin to return if the robotUnitPrx is null

source/RobotAPI/gui-plugins/RobotUnitPlugin/RobotUnitControlDevicesWidget.cpp

@@ -114,6 +114,10 @@ namespace armarx
     void RobotUnitControlDevicesWidget::update(const ControlDeviceStatus& status)
     {
         std::lock_guard<std::recursive_mutex> guard {mutex};
+        if (!robotUnit)
+        {
+            return;
+        }
         if (!entries.count(status.deviceName))
         {
             add(robotUnit->getControlDeviceDescription(status.deviceName));

source/RobotAPI/gui-plugins/RobotUnitPlugin/RobotUnitLVL1ControllersWidget.cpp

@@ -93,6 +93,10 @@ namespace armarx
     void RobotUnitLVL1ControllersWidget::lVl1ControllerStatusChanged()
     {
         std::lock_guard<std::recursive_mutex> guard {statusUpdatesMutex};
+        if (!robotUnit)
+        {
+            return;
+        }
         for (const auto& pair : statusUpdates)
         {
             lvl1ControllerCreated(pair.second.instanceName);
@@ -104,6 +108,10 @@ namespace armarx
     void RobotUnitLVL1ControllersWidget::lvl1ControllerCreated(std::string name)
     {
         std::lock_guard<std::recursive_mutex> guard {mutex};
+        if (!robotUnit)
+        {
+            return;
+        }
         if (!entries.count(name))
         {
             entries[name] = new RobotUnitLVL1ControllersWidgetEntry(*this, *(ui->treeWidget), robotUnit->getLVL1ControllerDescription(name));

source/RobotAPI/gui-plugins/RobotUnitPlugin/RobotUnitSensorDevicesWidget.cpp

@@ -66,6 +66,10 @@ namespace armarx
     void RobotUnitSensorDevicesWidget::sensorDeviceStatusChanged()
     {
         std::lock_guard<std::recursive_mutex> guard {statusUpdatesMutex};
+        if (!robotUnit)
+        {
+            return;
+        }
         for (const auto& pair : statusUpdates)
         {
             if (!entries.count(pair.second.deviceName))