Yes we can, I didn't implement because we don't have a lack of fv_converter API exception rules.
Next snippet code from oniguruma/sample/syntax.c for `onig_new`.
```
    char s[ONIG_MAX_ERROR_MESSAGE_LEN];
    onig_error_code_to_str(s, r, &einfo);
    fprintf(stderr, "ERROR: %s\n", s);
```