additional error checks

Author: buttonsbond

gateway_sumup.nbe

@@ -24,7 +24,7 @@ copyright=(C) 2021 All Tech Plus Rojales. All rights reserved.
 license=See file comments
 author_email=support@all-tech-plus.com
 author_url=www.all-tech-plus.com
-version=1.4.18
+version=1.4.21
 description=NBILL_SUMUP_DESC
 file=sumup/sumup.php
 admin_file=admin.sumup/sumup.php