[Bug]: Unexpected exception with unquoted multibyte identifier

[m15a]

What happened?

I tried to lint a piece of DuckDB code with the following configuration (.sqruff):

[sqruff]
dialect = duckdb

Linting the following code (example_1.sql) just works:

SELECT
    "日本語"
FROM
    's3://some.parquet';

❯ sqruff lint example_1.sql
The linter processed 1 file(s).
All Finished 📜 🎉

However, linting the following code (example_2.sql) fails:

SELECT
    日本語
FROM
    's3://some.parquet';

❯ sqruff lint example_2.sql

thread 'main' (10924345) panicked at crates/lib/src/rules/convention/cv03.rs:85:14:
called `Option::unwrap()` on a `None` value
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
== [example_2.sql] FAIL
L:   1 | P:   1 | ???? | Unexpected exception. Could you open an issue at
                       | https://github.com/quarylabs/sqruff
The linter processed 1 file(s).
All Finished 📜 🎉

I confirmed that this also happens when dialect = postgres.

Version

• sqruff version: 0.29.3

Checked in Playground

• I have checked this bug in the playground.

[pbowman2snap]

Can confirm it also happens with bigquery