validator isNull is deprecated

[guillaume-miara]

As per validatorjs/validator.js#505
the method is deprecated

It will throw : TypeError: _validator2.default.isNull is not a function

Must be replaced by isEmpty()

[maxefi]

correct me if it's not even better to replace it with lodashs isEmpty, since it's already being used.

[iqbalsafian]

https://www.npmjs.com/package/validator