ReferenceField always display

Hello, thanks you for your project. I think there is a bug with ReferenceField. When I use ReferenceField and the source is null, the loading appears but remains indefinitely. I have the impression that the field does not check before if the source is not null.

I was able to correct this by doing it like that but I think there must be a better solution:

const ConditionalReferenceField = ({ record, ...rest }) =>
  record && record[rest.source] ? (
    <ReferenceField {...rest}>
      <TextField source="name" />
    </ReferenceField>
  ) : null;

• React-admin version: 2.3.3
• Last version that did not exhibit the issue (if applicable): no applicable
• React version: 16.5.2
• Browser: Chrome
• Stack trace (in case of a JS error): no

[TomJannes]

I think you can use the allowEmpty={true} attribute on the ReferenceField

[fzaninotto]

Refixed in #3550