Function lex_valid

crates/ruff_python_parser/src/lexer.rs:1661–1674

(source: &str, mode: Mode, start_offset: TextSize)

    #[track_caller]
    fn lex_valid(source: &str, mode: Mode, start_offset: TextSize) -> LexerOutput {
        let output = lex(source, mode, start_offset);

        if !output.errors.is_empty() {
            let mut message = "Unexpected lexical errors for a valid source:\n".to_string();
            for error in &output.errors {
                writeln!(&mut message, "{error:?}").unwrap();
            }
            writeln!(&mut message, "Source:\n{source}").unwrap();
            panic!("{message}");
        }

        output
    }

    #[track_caller]
    fn lex_invalid(source: &str, mode: Mode) -> LexerOutput {