getDerivedStateFromProp must return null if no change

[yoyo837]

A valid state object (or null) must be returned. You have returned undefined.

First of all, thank you for your contribution! :-)

Please makes sure that these checkboxes are checked before submitting your PR, thank you!

• Make sure that you propose PR to right branch: bugfix for master, feature for latest active branch feature-x.x.
• Make sure that you follow antd's code convention.
• Run npm run lint and fix those errors before submitting in order to keep consistent code style.
• Rebase before creating a PR to keep commit history clear.
• Add some descriptions and refer relative issues for you PR.

Extra checklist:

if isBugFix :

• Make sure that you add at least one unit test for the bug which you had fixed.

elif isNewFeature :

• Update API docs for the component.
• Update/Add demo to demonstrate new feature.
• Update TypeScript definition for the component.
• Add unit tests for the feature.

[yoyo837]

Related: #10309

[ant-design-bot]

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[codecov]

Codecov Report

Merging #11398 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master   #11398      +/-   ##
==========================================
+ Coverage   91.76%   91.76%   +<.01%     
==========================================
  Files         199      199              
  Lines        5014     5015       +1     
  Branches     1403     1403              
==========================================
+ Hits         4601     4602       +1     
  Misses        408      408              
  Partials        5        5

Impacted Files	Coverage Δ
components/date-picker/createPicker.tsx	96.87% <100%> (+0.04%)	⬆️

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