Double quotes dilemma in JSON validation, when variable sometimes null

Hi, everyone!

I’m trying to make api post request with variable. Sometimes variable is null, and sometimes it has value.
“UpdatedYT”: “{{updated}}”
I can’t figure out what I should do with double quotes.
I can’t remove quotes, because Wappler doesn’t allow to save it (cause it wouldn’t be valid json).
And I can’t work with quotes, because “Задачи/UpdatedYT”: “null” isn’t vaild either and because of that I get bad response.