How to tackle with multiple attachments in Notification service if any one of them is empty in OIC?

I have an integration with notification action to send email with attachment if present but the problem here is that I have multiple file references as attachment mapped to the notification action. If even one of the file references is not generated and any of the attachment is empty, then the notification action is failing to send email.

I want email to be send with the available attachments or no attachment if file references are empty.

How can this be tackled? I don't want to create n number of switch cases for this as that will become huge.