Invoice Payment Method V 23Dec2018, PHP warnings on foreign language site

Still upgrading to V157, PHP739, Responsive classic green template

Added this Invoice Payment Method plugin and it works fine in English but got some PHP warnings in my German site.
The warnings below are about AUTHORIZENET and FIRSTDATA; I do not use any of these payment methods.
I could fix the problem and stop the warnings by defining each "status" as false in each payment method in \languages\german\modules\payment

PHP Warning: Use of undefined constant MODULE_PAYMENT_AUTHORIZENET_STATUS

PHP Warning: Use of undefined constant MODULE_PAYMENT_AUTHORIZENET_AIM_STATUS

PHP Warning: Use of undefined constant MODULE_PAYMENT_FIRSTDATA_PAYMENTPAGES_STATUS

Those Warnings can be safely ignored in this case. They are not errors that will cause code execution problems.

That said, the fastest "fix" without a full upgrade, is to delete all modules that you don't use. That way the system won't try to check whether they're enabled.

To do that, delete files for modules not in use, in the following directories. It's important that BOTH the module and its associated language file (in all languages) be removed, else errors will occur.

/includes/modules/payment/XXXXXXX.php
/includes/languages/EACH_LANGUAGE_NAME/modules/payment/XXXXXXX.php

There are sometimes extra payment-provider-specific subdirectories at /includes/modules/payment/YYYYYY/ ... yes you can delete those if you're not using those providers.

I don't really recommend doing all this. But based on your various other posts I suspect this is the sort of thing you're wishing for.