pl.Series.str.slice fails with chinese character

[chuchiy]

Are you using Python or Rust?

python

What version of polars are you using?

0.10.15

What operating system are you using polars on?

windows

Describe your bug.

pl.Series.str.slice can not substr chinese characters

What are the steps to reproduce the behavior?

Example

df = pl.DataFrame(
    {
        "b": ["foo", "ham", "spam", "egg", "中文"],
    }
)
df[[pl.col('b').str.slice(1,1)]]

What is the actual behavior?

above code snippet will throw error

PanicException: A non-utf8 string was passed.: Utf8Error

What is the expected behavior?

slice(1, 1) should return ["o", "a", "p", "g", "文"]

[ritchie46]

Thanks, for the issue report. Forgot about UTF8, will fix it!

[ritchie46]

Fix upstream: jorgecarleitao/arrow2#568