Fix the issue: when helpNamespace property in helpProvider is empty, press F1 The program exits abnormally without no error exception popped out.

[SimonZhao888]

Fixes #11583

Proposed changes

• Add non-null validation of the HelpNamespace property of the HelpProvider control to ensure the validity of the property.

Customer Impact

• When helpNamespace property in helpProvider is empty, press F1 The program exits abnormally without no error exception popped out.

Regression?

• Yes

Risk

• Minimal

Screenshots

Before

After

Test methodology

• Manual

Accessibility testing

Test environment(s)

• 9.0.100-preview.6.24312.9

Microsoft Reviewers: Open in CodeFlow