bugfix – total_years not required

In render_field_settings($field).

Set required to true otherwise it will allow empty values and break the code elsewhere.

            acf_render_field_setting($field, array(
                'label'			=> __('Total Years', 'acf'),
                'instructions'	=> '',
                'name'			=> 'total_years',
                'type'			=> 'number',
                'min'           => 1,
                'max'           => 999,
                'required'      => true,
            ));