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Reproduction link

Steps to reproduce

Create <Slider> with prop step={null} and typescript yields an error that "null" is not an acceptable value.

What is expected?

That "null" value IS an acceptable value.
According to the docs it has a special meaning, and there's even an example in the AntD site with it - https://codesandbox.io/s/jxny9

What is actually happening?

In #26884 (v4.6.6) the ts definition was wrongly changed from step?: number | null to step?: number.

🔔 Probably was undetected since the error appears for --strictnullchecks/strict: true in tsconfig.json.