fix crash on shutdown

interface/src/Application.cpp

@@ -566,6 +566,9 @@ void Application::aboutToQuit() {
 }
 
 void Application::cleanupBeforeQuit() {
+
+    _entities.clear(); // this will allow entity scripts to properly shutdown
+
     _datagramProcessor->shutdown(); // tell the datagram processor we're shutting down, so it can short circuit
     _entities.shutdown(); // tell the entities system we're shutting down, so it will stop running scripts
     ScriptEngine::stopAllScripts(this); // stop all currently running global scripts

libraries/entities-renderer/src/EntityTreeRenderer.cpp

@@ -969,6 +969,10 @@ void EntityTreeRenderer::checkAndCallUnload(const EntityItemID& entityID) {
             QScriptValueList entityArgs = createEntityArgs(entityID);
             entityScript.property("unload").call(entityScript, entityArgs);
         }
+        
+        // In the event that the entity script connected to any of our signals
+        // we want to disconnect it so we don't have anything dangling
+        _entitiesScriptEngine->disconnect(entityScript.toQObject());
     }
 }