fix: make sure that when calling Log no other process is Updating the struct

[manuelarte]

Based on the conversation in https://gophers.slack.com/archives/C02A3DRK6/p1789938584440119?thread_ts=1789931366.728789&cid=C02A3DRK6 it can happen that when calling the defer function that logs the entry, another goroutine is updating the struct.

Kudos to https://github.com/Snawoot for the feedback