Nintex Form doesn't like you to make mistake

I have experienced this a few times developing a Nintex Forms when previewing a form I have just designed:

Nintex Form blank

and I always ended up to delete some rules, re-create them, re-check all of them just to find which of my fields’ rule was not hidden by itself but would hide the whole form.

I just managed to repeat the issue several times and it just lays with a missing parenthesis in a rule formula (!)

missing character in Nintex Form rule formula 

Obvious but when you have dozen of fields and rules, it would be nice that Nintex Forms preview doesn’t load and simply returns an “error” rather than just a blank form, right ?