Exclusive gateway empty string check

I’m trying to check if a field named Error is empty in an exclusive gateway workflow step.

I have a record with a string field called Error.
When I check the record’s Error field value, it’s never null,empty or equal to the literal "" string.

My workflow gateway logic is this (you can see I was trying any way forward)


But even though the field is empty in the UI and null in the DB, the gateway always chooses the False path. When I alert the Error field value using a prompt it comes up as interface

Prompt definition:


What is the idiomatic way of empty string checking in a workflow?