Hello,
Unfortunately, I can't do a lot in that file ; it's part of the Authorize SDK :
github.com/AuthorizeNet/sdk-php/blob/mas...tSensitiveFields.php
Warning are active in my development website and I do not have these messages.
All I can tell you is, if the variable is invalid, it means that the decoding of your configuration file is not working so you have an error there.
Yes, you MUST hide all PHP messages to your customers and just log them into a file ; that is a requirement for all production websites (otherwise, it's a security problem).
Of course it's better to check all warnings and try to fix them ; since the file is part of the official Authorize SDK, I'm sorry but I cannot modify it in my side.
And I clearly can't tell you why you have the error since the system is made to use the configuration which is the json next to the PHP file.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.