nullable warnings

[JoC0de]

• annotate code with resharper nullable attributes. We can't use nullable reference types until we update / set minimum required version to Unity 2020.2
• add missing null-checks / cases
• extract update checker form NugetWindow
• rename asmdef

[igor84]

Nice work. It is sad we can't just use nullable reference types since they are only available since Unity 2020, I think. BTW. How do we decide when we can move the minimal supported version up?

[igor84]

Why do you need NonSerialized attribute on private field?

[JoC0de]

I was getting the warning CA2235:Mark all non-serializable fields without. I think the warning is not Unity related and doesn't apply to Unity. But I also found it useful for 'clarification'.

[JoC0de]

Nice work. It is sad we can't just use nullable reference types since they are only available since Unity 2020, I think. BTW. How do we decide when we can move the minimal supported version up?

I don't know. I also thought about it. Are there any statistics of which versions are actively used? Just googled it but i could only found some really old stats. I don't know how games handle Unity updates if they work for years before releasing the Game and also maintaining / updating the game constantly, are they freezed on one Unity version? I am not a Game developer 😄

[igor84]

There are probably all kind of use cases. In my company where we develop mobile games we are mostly trying to update to new LTS within six months from release. Some old games that are not maintained any more are on older version but we don't actually open them in Unity any more. Plus even if we wanted to build a new release of some old game we would probably have to update Unity first because of all the yearly breaking changes by Android and iOS.

On the other hand, desktop games probably don't have such hard limits to push them to update Unity so I would expect a lot of them get stuck on some old version where they have last seen active development.

Anyway 2022 LTS was released this year which I think means that 2020 LTS is no longer supported since Jun and since we are supporting from 2018 that means we are supporting last 3 releases that are not supported by Unity any more. When I put it like this it sounds reasonable. We could reduce it to 2 such releases but probably not more...

[JoC0de]

I will just merge this. We can easily (with one click) convert them to nullable reference types if we update Unity.