Regex findPattern for empty google sheets cells?

[logan-life]

When I import my transactions and then export them to Google Sheets, sometimes a given cell in some given column is empty.

For particular use cases, I want to be able to replace the empty value with some other value.

I am having a hard time figuring out how to correctly specify the findPattern in my mintable.jsonc to replace an empty cell with some other value.

Any help would be much appreciated.