'Null' class

[agentsquidflaps]

When trying to use the PostContacts method, if an option has not been added, for example, a custom data field called 'TYPE', then even though the contact gets successfully added to dotmailer, I'm thrown a response error 'Cannot use 'Null' as class name as it is reserved'

Edit - Just seen you've done a fix for this, but when installed with composer, this fix is not applied