Move update next slot cache earlier

[terencechain]

Update next slot cache currently happens after many things.

• forkchoice methods
• setter methods

This PR moves it earlier to the right after update head and only if it's head. There's no reason to wait for this

[potuz]

I don't think we want this, we want at the very least to have run forkchoice to ascertain the incoming block was head or similar. Even in the current implementation syncing an old non canonical block will corrupt the nsc with mostly useless info. I think you want to move it here so that you can have it before FCU and thus use it to get the payloadattributes. I suspect it's best to do it after forkchoice and only for canonical blocks

[terencechain]

I don't think we want this, we want at the very least to have run forkchoice to ascertain the incoming block was head or similar. Even in the current implementation syncing an old non canonical block will corrupt the nsc with mostly useless info. I think you want to move it here so that you can have it before FCU and thus use it to get the payloadattributes. I suspect it's best to do it after forkchoice and only for canonical blocks

Currently, today's behavior, it's triggered based on a newly arrived block, not a canonical block. This PR doesn't change it but I get what you meant by altering the behavior to only update NSC for the canonical block. I can update to that