fix(ext/node): avoid own `toString` on error instances

[LiviaMedeiros]

These errors shouldn't have enumerable toString properties.

The implementation is identical to the inherited from NodeErrorAbstraction, so overrides look redundant.

[bartlomieju]

Thanks for the PR @LiviaMedeiros, but it appears it causes some failures in compatibility tests from the Node.js codebase.

[LiviaMedeiros]

Couldn't reproduce the failures locally; let's see if redefining them as non-enumerable works.

[ry]

closing this because it's old