What's the difference between "states" (times) when `inRenderingTransaction == false` and when `currentState == null`? Why do we have two "flags"? Note that if we call `update` [during these lines](https://github.com/Raynos/main-loop/blob/v3.2.0/index.js#L72-L77) seems like [nothing would be happened](https://github.com/Raynos/main-loop/blob/v3.2.0/index.js#L49).