Date & DateTime widgets do not respect falsy/null/non-date ui:emptyValue

[thgreasi]

Prerequisites

• I have searched the existing issues
• I understand that providing a SSCCE example is tremendously useful to the maintainers.
• I have read the documentation
• Ideally, I'm providing a sample JSFiddle or a shared playground link demonstrating the issue.

What theme are you using?

core

Version

4.1.1

Current Behavior

For Date & DateTime fields of type "type": ["string", "null"], that do have "ui:emptyValue": null configured, clearing the input results the property to be completely removed from the result object.

Expected Behavior

For Date & DateTime fields of type "type": ["string", "null"], configured with "ui:emptyValue": null in their UISchema, should set a null value in the result object, consistently with how string & number fields behave.

Steps To Reproduce

1. go to to this shared playground.
2. set a value to the text, number, date & datetime fields and clear them afterwards.
3. while for the text & numeric fields the result object will have a property with null as a value, the form will not include at all properties for the date & datetime fields.

Environment

- OS: Ubuntu 20.04
- Node: 16.15.1
- npm: 8.12.2

Anything else?

No response

[heath-freenome]

Fixed in the v5 beta, see the 5.x migration guide