fix segfault in bullet cleanup routine

integrations/bullet/src/simulation.cpp

@@ -195,7 +195,9 @@ namespace fggl::phys::bullet {
 		auto entRB = m_ecs->find<BulletBody>();
 		for (const auto& ent : entRB) {
 			auto& bulletBody = m_ecs->get<BulletBody>(ent);
-			m_world->removeCollisionObject(bulletBody.body);
+			if ( bulletBody.body != nullptr ) {
+				m_world->removeCollisionObject(bulletBody.body);
+			}
 
 			// release resources and delete
 			bulletBody.release();