Working with blank fields

In my workflow 'Ecwid to Sheets', I keep getting an error while trying to save an action step where blank fields are being submitted.
Pls refer to the action step no. 7 for creating a google calendar detailed event. In the Description field, the values for shippingPerson street and shippingPerson city are null. Pabbly is giving an error here and not allowing me to save this step. However, I am ok with the values being null.
How do I overcome this situation?

Try using Text Formatter - Default Value