[Windows] Fixed NRE when clearing ListView after navigating back

[SubhikshaSf4851]

RootCause:

• The issue arises because the CollectionChanged event of the virtual view was not unwired in the DisconnectHandler method in ListViewRender. As a result, the CollectionChanged event was wired multiple times for each navigation, and it was never unwired. When we use the saved instance, the CollectionChanged event is wired for the second time, while the first one was never unwired. When we clear the item source, the CollectionChanged event is triggered for the first element. Since it was disconnected, we receive the virtual view as null.

Description Of Change:

• I have unwired the CollectionChanged event in the DisconnectHandler method.

Tested the behaviour in the following platforms.

• Windows

Issue Fixed:
Fixes #26498

Before Fix:

Issue26498BeforeFix.mp4

After Fix:

Issue26498AfterFix.mp4

[SubhikshaSf4851]

@dotnet-policy-service agree company="Syncfusion, Inc."

[jsuarezruiz]

/azp run

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[jsuarezruiz]

/azp run

[Mark-NC001]

@SubhikshaSf4851 I have tried your fix on my repro (I logged 26577, which has been closed as duplicate of 26498) - and the fix does stop the error, thank you.

[jsuarezruiz]

/azp run

[jfversluis]

/rebase

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