DYN-6997 Fix crash when view is null for nodes

[zeusongit]

Purpose

https://jira.autodesk.com/browse/DYN-6997

Crash StackTrace:

INFO 2024-05-16 11:12:22,590  - 0000003243efea30 00007ff89f3758b6 dynamocorewpf!_NA_::Dynamo.Controls.NodeView.topControl_MouseLeftButtonDown(System.Object, System.Windows.Input.MouseButtonEventArgs) 0xB6 [E:\Builds\Dynamo_RC3.0.3_master\Dynamo\src\DynamoCoreWpf\Views\Core\NodeView.xaml.cs @ 425]
INFO 2024-05-16 11:12:22,590  - 0000003243efeac0 00007ff89b725a8a presentationcore!_NA_::System.Windows.RoutedEventArgs.InvokeHandler(System.Delegate, System.Object) 0x8A 
INFO 2024-05-16 11:12:22,590  - 0000003243efeb10 00007ff89b728c7d presentationcore!_NA_::System.Windows.EventRoute.InvokeHandlersImpl(System.Object, System.Windows.RoutedEventArgs, Boolean) 0x6DD 
INFO 2024-05-16 11:12:22,590  - 0000003243efebe0 00007ff89c162473 presentationcore!_NA_::System.Windows.UIElement.ReRaiseEventAs(System.Windows.DependencyObject, System.Windows.RoutedEventArgs, System.Windows.RoutedEvent) 0xC3 

Don't know under what setup the user triggered the click action that they got a null view, but the PR now handles a nullable view variable. I can log this to console in a try-catch as well, if preferred.

Declarations

Check these if you believe they are true

• The codebase is in a better state after this PR
• Is documented according to the standards
• The level of testing this PR includes is appropriate
• User facing strings, if any, are extracted into *.resx files
• All tests pass using the self-service CI.
• Snapshot of UI changes, if any.
• Changes to the API follow Semantic Versioning and are documented in the API Changes document.
• This PR modifies some build requirements and the readme is updated
• This PR contains no files larger than 50 MB

Release Notes

• Handle crash on node top click

Reviewers

@DynamoDS/dynamo

[github-actions]

See the ticket for this pull request: https://jira.autodesk.com/browse/DYN-6997

[github-actions]

UI Smoke Tests

Test: success. 2 passed, 0 failed.
TestComplete Test Result
Workflow Run: UI Smoke Tests
Check: UI Smoke Tests - net8.0

[reddyashish]

@zeusongit Do we need this for 3.2?

[QilongTang]

This is currently scheduled on 3.3 release, fine to not cherry-pick