Pull Request for Issue #38759 .

Summary of Changes

Added null coalescing check to prevent null warning.

Testing Instructions

In the backend:

1. Navigate to Menu Home dashboard
2. Click Global configuration, in TAB "Server", set Error Reporting to "Maximum".
3. Navigate to Menu System
4. Click Administrator Template Styles, open your active style which should be "Atum - Default".
5. In TAB "Image Settings", Select a "Brand Large" image, leave Image description empty and check the "No Description" box.
6. Select a "Brand Small" image, leave Image description empty and check the "No Description" box.
7. Click SAVE.

Actual result BEFORE applying this Pull Request

There were two depreaction warnings like:

Deprecated
: htmlspecialchars(): Passing null to parameter #1 ($string) of type string is deprecated in
\administrator\templates\atum\index.php
on line
56

Deprecated
: htmlspecialchars(): Passing null to parameter #1 ($string) of type string is deprecated in
\administrator\templates\atum\index.php
on line
59

Additional test case 2:

1. Try to test the error page by opening an not existing view like http://your-domain/administrator/index.php?view=xy
2. Test is successful when there is no PHP warning on the error page.

Additional test case 3:

1. Logout and navigate to backend login page
2. Test is successful when there is no PHP warning on the login page.

Expected result AFTER applying this Pull Request

There is no PHP 8.1 warning.

Documentation Changes Required

No