Quantity value check when adding new object to material list

[Zediwan]

When trying to add a new object to the material list of a "block" it is possible to enter values other than float but when trying to save then the error is displayed.
I think it would make sense to check for the type of input when the user is finished entering the value then displaying a warning and not just when saving the object.

[carlobeltrame]

Thanks for reporting! This is a duplicate of #4729, should be fixed with #5017. If you want to help us out, you can test whether it's really fixed on https://dev.ecamp3.ch

If it's working, the fix should be live on production with the next prod deployment (usually every few months, but the next one should be soon)

[pmattmann]

fixed by #5017