fix(module: datepicker): an exception is caused when passes the value as null

[ElderJames]

🤔 This is a ...

• New feature
• Bug fix
• Site / documentation update
• Demo update
• Component style update
• Bundle size optimization
• Performance optimization
• Refactoring
• Code style optimization
• Test Case
• Branch merge
• Other (about what?)

🔗 Related issue link

fixed #2676

💡 Background and solution

📝 Changelog

Language	Changelog
🇺🇸 English
🇨🇳 Chinese

☑️ Self Check before Merge

⚠️ Please check all items below before review. ⚠️

• Doc is updated/provided or not needed
• Demo is updated/provided or not needed
• Changelog is provided or not needed

[github-actions]

[codecov]

Codecov Report

Merging #2688 (a78035e) into master (9805945) will increase coverage by 1.23%.
The diff coverage is 40.00%.

@@            Coverage Diff             @@
##           master    #2688      +/-   ##
==========================================
+ Coverage   38.83%   40.07%   +1.23%     
==========================================
  Files         505      543      +38     
  Lines       33591    25670    -7921     
  Branches        0      260     +260     
==========================================
- Hits        13046    10287    -2759     
+ Misses      20545    15343    -5202     
- Partials        0       40      +40     

Impacted Files	Coverage Δ
components/date-picker/RangePicker.razor.cs	54.06% <40.00%> (+3.61%)	⬆️
components/breadcrumb/Breadcrumb.razor.cs	90.00% <0.00%> (-10.00%)	⬇️
components/core/Helpers/MemberPath/PathNode.cs	46.15% <0.00%> (-8.85%)	⬇️
components/avatar/AvatarGroup.razor	75.00% <0.00%> (-8.34%)	⬇️
components/core/Reflection/TypeDefined.cs	77.77% <0.00%> (-7.94%)	⬇️
components/input/InputGroup.razor.cs	87.50% <0.00%> (-6.95%)	⬇️
components/core/Helpers/DateHelper.cs	85.33% <0.00%> (-4.90%)	⬇️
...ponents/date-picker/types/DatePickerPlaceholder.cs	22.72% <0.00%> (-4.20%)	⬇️
...onents/date-picker/internal/DatePickerHeader.razor	41.86% <0.00%> (-3.21%)	⬇️
...ponents/core/Component/Overlay/type/TriggerType.cs	81.25% <0.00%> (-2.97%)	⬇️
... and 443 more

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