tarfile.TarFile.errors is initialized for some reason as None even though it really only accepts str

Bug report

Bug description:

See the exact line here: https://github.com/python/cpython/blob/ee57221872ad009df648e22d2f113f907607ec16/Lib/tarfile.py#L1687

After that the errors is used only as string in encode/decode. And is initialized in the dunder init with default errors="surrogateescape".

So perhaps it would be a good idea to use errors="" in #L1687 ? or directly with the default errors="surrogateescape" ?

This was discovered as part of the typeshed, where tarfile.TarFile.errors was added into the allowed list since mypy complained: https://github.com/python/typeshed/blob/2ccc53bb6716463680fcf1d204642c46299b7f88/stdlib/%40tests/stubtest_allowlists/common.txt#L46C1-L46C16

I will add a PR here and to the typeshed if this gets approved.

CPython versions tested on:

3.13

Operating systems tested on:

Windows

Start at Lib/tarfile.py line 1687 and inspect the TarFile initializer and the later encode/decode uses of errors. Check the related typeshed allowlist entry, then confirm the runtime initialization and typing agree; update the corresponding CPython and typeshed changes if needed.