Skip tamper if item is empty

Hi guys,

I need a help. I'm trying to import an image name from a json file which will be tampered to have the full url path using tamper.

The problem is, I can't find a settings to skip the tamper if the item is empty or the json file does not have the info for the image.

I am quite new and don't know how to write custom modules for this.

Thanks in advance,
Sean