Allow empty input on NumberInput

[richard-engineering]

Hello,

I'm using NumberInput because it strips out letters and is convenient. However I noticed that if I delete the number it does not in fact update the link associated with it. I use validate.js against the json object everything links to when the user submits to validate input. Thus it can result in differences between what is shown on the screen and the data. It would be good to have a prop on NumberInput to allow empty input to change the link (can set it to undefined or null).

Thanks!

[gaperton]

Setting it to null could be a good idea, thanks. I will make corresponding change.