Post function to add default value to null values

OL Connect Professional Designer
1

I have a field that extracts a currency value. Sometimes it is null. Is there a simple “Post function” to add default value of 0.00 to those values that are returned null? I’m currently getting the following message when a null value occurs

Error occurred [ Field FieldName]: Currency Sign is not found (DME000218)

2

Just tick the Treat empty as 0 option:

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