ZC v1.56c
PHP v7.2.10

In admin > modules > payment with Paypal EC and Square enabled I get these PHP warnings on a page refresh:

(this refers to paypal.php, the others refer to paypalwpp.php & square.php)

Code:
[24-Jul-2019 18:33:45 Europe/London] Request URI: /admin/modules.php?set=payment, IP address: 127.0.0.1
#1  CeonURIMappingLinkBuildAdmin->updateNotifySEFUInterceptAdmcathref() called at [D:\wamp64\www\mydomain.co.uk\includes\classes\class.base.php:103]
#2  base->notify() called at [D:\wamp64\www\mydomain.co.uk\admin\includes\functions\html_output.php:50]
#3  zen_catalog_href_link() called at [D:\wamp64\www\mydomain.co.uk\includes\languages\english\modules\payment\paypal.php:14]
#4  include(D:\wamp64\www\mydomain.co.uk\includes\languages\english\modules\payment\paypal.php) called at [D:\wamp64\www\mydomain.co.uk\admin\modules.php:192]
--> PHP Warning: Use of undefined constant ENABLE_SSL - assumed 'ENABLE_SSL' (this will throw an Error in a future version of PHP) in D:\wamp64\www\mydomain.co.uk\admin\includes\classes\observers\class.CeonURIMappingLinkBuildAdmin.php on line 46.
relevant lines in admin\includes\classes\observers\class.CeonURIMappingLinkBuildAdmin.php are:

Code:
if ($connection == 'NONSSL') {
						$link = HTTP_SERVER;
				} elseif ($connection == 'SSL') {
						if (ENABLE_SSL == 'true') {
								$link = HTTPS_SERVER;
						} else {
								$link = HTTP_SERVER;
						}
				}