Hi,
Branch does have two modes of operation distinguished by the “Evaluate Labels” property:
When “Evaluate Labels” is set to false you can branch over a specified field with fixed values as a label for each option (as shown above in the screenshot.
When “Evaluate Labels” is set to true there is no dedicated field specified at the branch step itself, but you can write complex conditions at the labels of each step. It is possible to use logical operators here to combine several conditions for one step.
In your case this would result in a condition like this:
data != $null && data != ""
Or you can check the length of the array and when it is 0, you exit the flow.
Regards,
Holger