Function invalid_utf8_value 

pub fn invalid_utf8_value<'t, 'v>(
    name: &'t str,
    bad: FromUtf8Error,
) -> Error<'t, 'v>

One Error::InvalidValue for a word that was not UTF-8.

The error half of what a generated build does per text field: the check stays inline at the field, and this — the lossy rendering and the allocations — lives here once instead of once per field.