Can some guide me on how to solve this  TypeError: self._super is not a function in odoo v12.
The error occurs on the bolded self._super() line in the code below
Thank you.

odoo.define('pos_allow_credit.pos', function (require) {
"use strict";

	var screens = require('point_of_sale.screens');
	var models = require('point_of_sale.models');
	var core = require('web.core');
	var rpc = require('web.rpc');
	var Session = require('web.Session');
	var PosBaseWidget = require('point_of_sale.BaseWidget');

	var QWeb = core.qweb;
	var _t = core._t;

	
	models.load_fields("res.partner", ['allow_credit']);
	screens.PaymentScreenWidget.include({
		finalize_validation: function() {
			var self = this;
	    	if(self.pos.partner.allow_credit){
	    		self._super();
    		} else {

    			rpc.query({
                        model: 'res.partner',
                        method: 'get_status',
                    })

    				.then(function(result){
    					self._super();
    				})
    				.fail(function (error, event){
    					event.preventDefault();
    					self.pos.gui.show_popup('error',{
    						'title': _t('Not Allowed'),
    						'body': _t("You are not Qualified"),
    					});
    					return;
    				});
    			}
    		}
    	});

});