[v25.x] lib: do not provide an empty Proxy from localStorage getter

[Renegade334]

Addresses the original regression in a way that is more consistent with the user experience in v24.x where no storage-related CLI arguments are passed. Access now warns and returns undefined in the case where the requisite path is missing.

As things stand, the behaviour will revert to exception-raising in v26.x; any discussion relating to this specifically should go in the associated issue, this PR is just to re-fix the regression for localStorage users in v25.

Refs: #60303

[github-actions]

The notable-change PRs with changes that should be highlighted in changelogs. label has been added by @Renegade334.

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/70252/

[RafaelGSS]

Landed in c57a40c

[aduh95]

c57a40c was removed from the staging branch, though I cannot reopen this PR (probably because the branch has been deleted).
FWIW, my opinion is that it's not worth touching localStorage in v25.x given the impact of the previous attempt, though I won't block someone trying – as long I'm not the one releasing the change.

[Renegade334]

@mcollina has submitted the equivalent to this PR against main in #61333. I suggest that we allow that to land on v25.x, providing releasers are amenable – users are still reporting headaches from the v25.0 regression on the associated issue.

[mcollina]

@Renegade334 it’s not exactly equivalent, it should correctly not mark localStorage as enumerable.