fix: fix nesting issue due to the errors order

[volodymyr-kushnir]

This fixes a nesting issue I've originally hit with the ajv resolver (albeit the issue itself is applicable to all resolvers) which is that toNestErrors may lose keys depending on the order of the keys returned by the parseErrorSchema, e.g. in this particular example the error for the config is actually last (the console output of parsedErrors is sorted thus a bit misleading) and simply replaces the config: { type: …, userId: … } object that existed one nesting step earlier —

I was explaining this to my coworkers so I have a screencast (100 seconds) that illustrates the issue, attaching it here in hope that it'd explain the changes behind the PR better than my writing —

resolvers.mp4

Also I was not very comfortable with passing the objects straight to Object.assign, I think I've hit a bug with objects being mutated in place, so even though I can no longer reproduce it I've still wrapped "foreign" objects in a structuredClone, just to be on a safe side.