Insert to database create empty record

Hi
I’m new to wappler and I’m very enthusiast.
I created a server action to add a new user to the database. The status when the form is submitted is 200 OK but it create an empty record to the database.
I then see this kid of error:

Capture d’écran 2020-06-15 à 09.53.374088×342 98.5 KB

Why?
Thanks