[Bug] Panic: Invalid UTF-8 byte index in string processing with multibyte characters

Question

**Bug Description**
thread '<unnamed>' (14984) panicked at /rustc/ed61e7d7e242494fb7057f2657300d9e77bb4fcb\library\core\src\str\mod.rs:833:21:
byte index 11 is not a char boundary; it is inside '파' (bytes 9..12) of `한계돌파", "lv1")),`
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

**Environment Info**
- Platform: win32
- Terminal: vscode
- Version: 2.0.76
- Feedback ID: 2e5e7de7-fc39-48b3-9119-d7603c01a0ba

**Errors**
```json
[]
```