ensure game scenes without cameras do not crash

fggl/gfx/ogl/renderer.cpp

@@ -207,7 +207,11 @@ namespace fggl::gfx {
 
 		if ( m_debugRenderer ) {
 			auto cameras = world.findMatching<gfx::Camera>();
-			auto cameraEnt = cameras[0];
+			if ( cameras.empty() ) {
+				return;
+			}
+
+			auto cameraEnt = cameras.front();
 
 			auto* const camTransform = world.get<math::Transform>(cameraEnt);
 			auto* const camComp = world.get<gfx::Camera>(cameraEnt);

fggl/scenes/game.cpp

@@ -43,6 +43,8 @@ namespace fggl::scenes {
 	}
 
 	void Game::update() {
+		assert( m_world );
+
 		if ( m_input != nullptr ) {
 			bool escapePressed = m_input->keyboard.pressed(glfwGetKeyScancode(GLFW_KEY_ESCAPE));
 			if (escapePressed) {