Interval is not a number

[arthurzenika]

When filling the form and not touching the 30 in interval :

I guess it doesn't take into the example value.

And I think it probably needs an asterix to show it's mandatory.

[jlecour]

Hi @arthurlogilab and thank you for submitting this issue.

The placeholder style is definitely misleading and should more explicit or removed.
I even guess we should put a default value here instead of a useless placeholder.

Regarding the "required" state of the field, you're also right. We'll add something.