JointPositionController: Improve misleading error message

src/rendering/SceneManager.cc

@@ -513,8 +513,7 @@ rendering::MaterialPtr SceneManager::LoadMaterial(
     }
     else
     {
-      const sdf::PbrWorkflow *specular=
-          pbr->Workflow(sdf::PbrWorkflowType::SPECULAR);
+      auto specular = pbr->Workflow(sdf::PbrWorkflowType::SPECULAR);
       if (specular)
       {
         ignerr << "PBR material: currently only metal workflow is supported. "

src/systems/joint_position_controller/JointPositionController.cc

@@ -20,6 +20,7 @@
 #include <ignition/msgs/double.pb.h>
 
 #include <string>
+#include <unordered_set>
 
 #include <ignition/common/Profiler.hh>
 #include <ignition/math/PID.hh>
@@ -206,21 +207,24 @@ void JointPositionController::PreUpdate(
     _ecm.CreateComponent(
         this->dataPtr->jointEntity, components::JointPosition());
   }
-  if (jointPosComp == nullptr)
+  // We just created the joint position component, give one iteration for the
+  // physics system to update its size
+  if (jointPosComp == nullptr || jointPosComp->Data().empty())
     return;
 
   // Sanity check: Make sure that the joint index is valid.
   if (this->dataPtr->jointIndex >= jointPosComp->Data().size())
   {
-    static bool invalidJointReported = false;
-    if (!invalidJointReported)
+    static std::unordered_set<Entity> reported;
+    if (reported.find(this->dataPtr->jointEntity) == reported.end())
     {
       ignerr << "[JointPositionController]: Detected an invalid <joint_index> "
              << "parameter. The index specified is ["
-             << this->dataPtr->jointIndex << "] but the joint only has ["
+             << this->dataPtr->jointIndex << "] but joint ["
+             << this->dataPtr->jointName << "] only has ["
              << jointPosComp->Data().size() << "] index[es]. "
              << "This controller will be ignored" << std::endl;
-      invalidJointReported = true;
+      reported.insert(this->dataPtr->jointEntity);
     }
     return;
   }

src/systems/physics/Physics.cc

@@ -2207,8 +2207,7 @@ void PhysicsPrivate::UpdateSim(EntityComponentManager &_ecm)
         if (auto jointPhys = this->entityJointMap.Get(_entity))
         {
           _jointPos->Data().resize(jointPhys->GetDegreesOfFreedom());
-          for (std::size_t i = 0; i < jointPhys->GetDegreesOfFreedom();
-               ++i)
+          for (std::size_t i = 0; i < jointPhys->GetDegreesOfFreedom(); ++i)
           {
             _jointPos->Data()[i] = jointPhys->GetPosition(i);
           }