Add error to form (after submit) programmatically?

Hi,

In v2.9.7 I used following to add error to form (during ninja_forms_preprocess hook)

add_action('ninja_forms_pre_process', 'dpcontent_pre_process_ninja_form');
function dpcontent_pre_process_ninja_form() {
    global $ninja_forms_processing;
    $ninja_forms_processing->add_error(1, 'Error submitting your enquiry');

How do add error to a form after submission in NF v3?

I currently have:

// NF3 Form processing:
add_action( 'ninja_forms_after_submission', 'dpcontent_ninja_forms_after_submission' );

function dpcontent_ninja_forms_after_submission($form_data) {
    
    // Form processing settings
    $form_processing_id = $form_data['form_id'];
    $form = Ninja_Forms()->form($form_processing_id);

    // Error in processing, how to add error to form? (no add_error(id, msg) method on NF_Form type) 
   ...