gh-130167: Improve the error case for textwrap.dedent

[AA-Turner]

cc @hroncok @picnixz

• Issue: Improve speed of stdlib functions by replacing re uses #130167

[hroncok]

Would it be possible to add a test for this?

[hroncok]

Thanks. I suppose bytes would still TypeError implicitly, right?

[AA-Turner]

Yes, but with an error message from bytes.split. I've pushed an improvement.

[picnixz]

Out of curiosity, can we have the benchmarks for this change on empty strings? I don't think we lose much but I'm just curious.

[AA-Turner]

I won't have time in the near future to run benchmarks.

A