JEventPool is now responsible for setting JEvent app ptr

Previously, it was the JEventSource, which doesn't work in the case of TimesliceExample, because PhysicsEvents come straight from the pool.

src/libraries/JANA/JEventSource.h

@@ -192,7 +192,6 @@ class JEventSource : public jana::omni::JComponent, public jana::omni::JHasOutpu
 
             // We configure the event
             event->SetEventNumber(m_event_count); // Default event number to event count
-            event->SetJApplication(m_app);
             event->SetJEventSource(this);
             event->SetSequential(false);
             event->GetJCallGraphRecorder()->Reset();

src/libraries/JANA/JFactory.cc

@@ -10,7 +10,8 @@
 void JFactory::Create(const std::shared_ptr<const JEvent>& event) {
 
     // We need this for JMultifactoryHelper. Eventually it should go away
-    SetApplication(event->GetJApplication());
+    auto app = event->GetJApplication();
+    if (app != nullptr) SetApplication(app);
 
     if (mStatus == Status::Uninitialized) {
         CallWithJExceptionWrapper("JFactory::Init", [&](){ Init(); });

src/libraries/JANA/Omni/JComponentFwd.h

@@ -85,7 +85,12 @@ struct JComponent {
         return m_status; 
     }
 
-    void SetApplication(JApplication* app) { m_app = app; }
+    void SetApplication(JApplication* app) { 
+        if (app == nullptr) {
+            throw JException("Attempting to set a null JApplication pointer!");
+        }
+        m_app = app; 
+    }
 
     void SetLogger(JLogger logger) { m_logger = logger; }
 

src/libraries/JANA/Services/JComponentManager.cc

@@ -108,6 +108,7 @@ void JComponentManager::configure_event(JEvent& event) {
     event.SetFactorySet(factory_set);
     event.SetDefaultTags(m_default_tags);
     event.GetJCallGraphRecorder()->SetEnabled(m_enable_call_graph_recording);
+    event.SetJApplication(GetApplication());
 }