Add a null-check for "DataGridView" property before executing OnMouseUp in function OnMouseUpInternal

[LeafShi1]

Fixes #12692

Root Cause

• This issue is caused by PR Enable nullability in remaining DataGridViewCell members #10406，which removes the check whether the control is null before executing OnMouseUp in file DataGridViewCell.cs

Proposed changes

• Add a check if DataGridView is not null before executing OnMouseUp in function OnMouseUpInternal, because the Parent DataGridView might have been disconnected in the user event handler that is executed before this call, for example if the user clears the DataGridView row.

Customer Impact

• Application crashes when the customer clicks on a DataGridView cell, where previously the content was selected.

Regression?

• Yes, from NET8

Risk

• Minimal

Screenshots

Before

Object reference not set to an instance of an object exception pops up after clicked the DataGridViewCell content when the function DataGridView1_CellContentClick contains content
DataGridView1.Rows.Clear();
DataGridView1.Rows.Add(1, 0, "ABCD");

After

DataGridView Rows can be cleaned and re-added normally

Test methodology

• Manually, added a unit test

Test environment(s)

• .net 10.0.0-alpha.1.24631.2

Microsoft Reviewers: Open in CodeFlow

[codecov]

Codecov Report

Attention: Patch coverage is 95.83333% with 1 line in your changes missing coverage. Please review.

Project coverage is 76.12895%. Comparing base (9007f33) to head (0b9a711).
Report is 27 commits behind head on main.

Additional details and impacted files

@@                 Coverage Diff                 @@
##                main      #12701         +/-   ##
===================================================
+ Coverage   76.00638%   76.12895%   +0.12257%     
===================================================
  Files           3181        3188          +7     
  Lines         639670      640106        +436     
  Branches       47215       47233         +18     
===================================================
+ Hits          486190      487306       +1116     
+ Misses        149968      149269        -699     
- Partials        3512        3531         +19     

Flag	Coverage Δ
Debug	76.12895% <95.83333%> (+0.12257%)	⬆️
integration	18.16321% <0.00000%> (+0.11730%)	⬆️
production	50.01476% <75.00000%> (+0.24972%)	⬆️
test	97.02618% <100.00000%> (-0.00270%)	⬇️
unit	47.24991% <75.00000%> (+0.19892%)	⬆️

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[ricardobossan]

I tested the PR code, and the issue appears to be resolved:

LGTM!

[Tanya-Solyanik]

Thank you for jumping on this issue! Looks good, I added only minor comments.
Could you please also review the rootcause PR for similar cases, for example other instances of invocations of user-provided event handlers that are followed by an access to the parent DGV?

[LeafShi1]

Thank you for jumping on this issue! Looks good, I added only minor comments. Could you please also review the rootcause PR for similar cases, for example other instances of invocations of user-provided event handlers that are followed by an access to the parent DGV?

Will do that and share my findings once the review is complete.

[Tanya-Solyanik]

One way to investigate if we have similar cases with other event handlers is to add unit tests like this one for different events.

[LeafShi1]

From the root cause PR, other changes seem different from this situation?

For this case "calling other instances of the user-provided event handler and then accessing the parent DGV", the change of the event OnMouseUpInternal does meet this situation, but it only adds a judgment of

if (DataGridView is null)
{
     return;
}

Do we also need to add a test similar to this?

[Tanya-Solyanik]

@LeafShi1 - review is practically complete, the only remaining step is the investigation of similar cases. We would want to service all duplicates at once.