Function remove_line 

pub(crate) fn remove_line(
    qt: &CxxQtThread<Sioul>,
    shared: &Arc<Shared>,
    uri: &str,
    shown: &str,
) -> String

One line of the budgets’ file taken out (sioul:budget/<budget>/<place>), only when it is still the line the page showed (shown: its row, JSON); returns what went wrong, else “”.