PropertyGridView: Prevent out-of-range access when committing next enumerable value

[LeafShi1]

Fixes #14169, #14170

Root cause:

The PropertyGrid assumes that the StandardValues list is stable and non‑empty once the current index is computed.
However, during both double‑click value cycling and mouse‑wheel value cycling, the control calls GetPropertyValueList() a second time when committing the next value.
In certain scenarios (dynamic TypeConverters, context‑dependent StandardValues, or volatile data sources), this second call may return an empty array, making the previously computed index invalid.
This leads to an out‑of‑range access when executing:

CommitValue(values[index])

Proposed changes

• Update method DoubleClickRow and OnMouseWheel: After calling gridEntry.GetPropertyValueList(), check values.Length > 0 before trying to access values[index].

Customer Impact

• Prevents IndexOutOfRangeException or similar crashes when users double‑click or scroll a PropertyGrid entry whose StandardValues list becomes empty at commit time.

Regression?

• No

Risk

• Minimal

Screenshots

WinFormsApp18.zip

Before

Double‑clicking or scroll the mouse wheel in the attribute value editing box, GetPropertyValueList() may return an empty array

BeforeChanges.mp4

After

Logic re‑verifies the StandardValues list before using it.
If values.Length == 0, cycling is safely skipped.
No exceptions are thrown

AfterChanges.mp4

Test methodology

• Manually

Test environment(s)

• .net 11.0.0-alpha.1.25619.109

Microsoft Reviewers: Open in CodeFlow

[codecov]

Codecov Report

❌ Patch coverage is 0% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.14364%. Comparing base (05b7c2e) to head (6873346).

Additional details and impacted files

@@                 Coverage Diff                 @@
##                main      #14182         +/-   ##
===================================================
- Coverage   77.15877%   77.14364%   -0.01513%     
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  Files           3279        3279                 
  Lines         645333      645339          +6     
  Branches       47720       47722          +2     
===================================================
- Hits          497931      497838         -93     
- Misses        143719      143813         +94     
- Partials        3683        3688          +5     

Flag	Coverage Δ
Debug	77.14364% <0.00000%> (-0.01513%)	⬇️
integration	18.99429% <0.00000%> (-0.00981%)	⬇️
production	51.99632% <0.00000%> (-0.03339%)	⬇️
test	97.40559% <ø> (ø)
unit	49.43828% <0.00000%> (-0.00416%)	⬇️

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Pull request overview

This PR fixes IndexOutOfRangeException crashes in PropertyGridView when users double-click or scroll with the mouse wheel on enumerable properties whose StandardValues list becomes empty between index calculation and value commit. The fix adds defensive checks to ensure the values array is not empty before attempting to access it by index.

Key Changes:

• Added empty array validation in DoubleClickRow method before cycling through enumerable values
• Added empty array validation in OnMouseWheel method before cycling through enumerable values with mouse wheel

[ricardobossan]

All LGTM!