Fix clippy errors.

src/compare/compare_field.rs

@@ -655,7 +655,7 @@ pub(crate) fn compare_property_number_lines<
         (Some(number_lines), Some(rust_number_lines)) => {
             let token_list = number_lines.as_list()?;
             let number_type = token_list
-                .get(0)
+                .first()
                 .map(Token::as_atom)
                 .map_or(Ok(None), |r| r.map(Some))?
                 .ok_or(":number-lines should have a type.")?;