Change warning about invoice balance when processing ERAs
Sometimes I apply a write-off before I process the ERA. When I process the ERA I receive a warning that the payment write-off leads to a negative balance, but that's not always the case. Change the message to say it might lead to a negative balance.
It would be helpful to not have the ERA error msg 'payment leads to negative invoice balance' when posting an era payment to an invoice that already has a write-off amount posted. The feature works fine, but the error message throws us off.
