Passing NULL to mb_strlen() with PHP 8.1 in Views UI module

Here would be my suggestion as a patch, recommendations and further evaluations are welcome.

For a bug report we need steps to reproduce the bug.

reroll patch, small error with the separator and thus duplicated string.

This should probably only fix the bug. Refactoring should be a separate issue. The more this is doing the more difficult it will be to have it committed.

The problem arose with the 'Agreement' module in version 3.0.0-alpha2 (an issue will follow in the project), the error message was the following:

Warning: Undefined array key "" in /var/www/html/docroot/core/modules/views_ui/src/ViewFormBase.php on line 162

Warning: Trying to access array offset on value of type null in /var/www/html/docroot/core/modules/views_ui/src/ViewFormBase.php on line 162

Deprecated: mb_strlen(): Passing null to parameter #1 ($string) of type string is deprecated in /var/www/html/docroot/core/modules/views_ui/views_ui.module on line 347
The website encountered an unexpected error. Please try again later.

Error: Call to a member function isEnabled() on null in Drupal\views_ui\ViewEditForm->getDisplayDetails() (line 421 of core/modules/views_ui/src/ViewEditForm.php).
Drupal\views_ui\ViewEditForm->getDisplayTab(Object) (Line: 212)
Drupal\views_ui\ViewEditForm->form(Array, Object) (Line: 107)
Drupal\Core\Entity\EntityForm->buildForm(Array, Object) (Line: 41)
Drupal\views_ui\ViewFormBase->buildForm(Array, Object)
call_user_func_array(Array, Array) (Line: 536)
Drupal\Core\Form\FormBuilder->retrieveForm('view_edit_form', Object) (Line: 283)
Drupal\Core\Form\FormBuilder->buildForm(Object, Object) (Line: 48)
Drupal\Core\Entity\EntityFormBuilder->getForm(Object, 'edit', Array) (Line: 230)
Drupal\views_ui\Controller\ViewsUIController->edit(Object, NULL)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 583)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 124)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array) (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 166)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 74)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 58)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle(Object, 1, 1) (Line: 704)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)

So I started to look in detail what the problem is, just discovered that the function views_ui_truncate() as described by me is not error free under PHP 8.1.

The problem with the contrib module Agreement has indirectly to do with the function I mentioned. However, I find that

• a) the function views_ui_truncate() should be made more error-tolerant, although most of the problems will probably have to do with contrib.
• b) Compatibility for PHP 8.1 must be made anyway.