Got the exact same.

I updated the server through the steamcmd, then reinstalled oxide but I'm getting these errors:

The referenced script (ElectricBattery) on this Behaviour is missing!
The referenced script on this Behaviour (Game Object 'large.rechargable.battery.deployed') is missing!
NullReferenceException: Object reference not set to an instance of an object

Does anyone knows how to fix this?

You are installing an old Oxide build, the error is from an old Rust version mixing with another. This can happen when using an old link, your host proving an outdated build, or the wrong build being used locally if it was downloaded in the past.

I'm reinstalling the server to see if it works. And btw, can you say me what is the oxide.covalence.data used for? I was looking for what files I would delete on wipe but I don't know what to do with this one

Player data for the universal plugin API. Generally safe to delete, just less information for offline usage.

Hmm, ok. And yep, after a fresh reinstall everything is working.