Steps to reproduce the issue

Install Beta6-dev Full package of 22 December.
Set error reporting to Maximum and Log Almost Everything.
Go to User Menu - Edit Account - Basic Settings.

Expected result

No PHP messages.

Actual result

Several PHP notices displayed.

System information (as much as possible)

Windows 10, Wampserver 3.2.4
Apache 2.4.46a, MySQL 8.0.22, PHP 7.4.13

Additional comments

Stack Trace

[22-Dec-2020 19:02:04 UTC] PHP Notice:  Trying to access array offset on value of type null in C:\www\joomla4\libraries\src\HTML\Helpers\Bootstrap.php on line 537
[22-Dec-2020 19:02:04 UTC] PHP Stack trace:
[22-Dec-2020 19:02:04 UTC] PHP   1. {main}() C:\www\joomla4\administrator\index.php:0
[22-Dec-2020 19:02:04 UTC] PHP   2. require_once() C:\www\joomla4\administrator\index.php:36
[22-Dec-2020 19:02:04 UTC] PHP   3. Joomla\CMS\Application\AdministratorApplication->execute() C:\www\joomla4\administrator\includes\app.php:63
[22-Dec-2020 19:02:04 UTC] PHP   4. Joomla\CMS\Application\AdministratorApplication->doExecute() C:\www\joomla4\libraries\src\Application\CMSApplication.php:266
[22-Dec-2020 19:02:04 UTC] PHP   5. Joomla\CMS\Application\AdministratorApplication->dispatch() C:\www\joomla4\libraries\src\Application\AdministratorApplication.php:185
[22-Dec-2020 19:02:04 UTC] PHP   6. Joomla\CMS\Component\ComponentHelper::renderComponent() C:\www\joomla4\libraries\src\Application\AdministratorApplication.php:142
[22-Dec-2020 19:02:04 UTC] PHP   7. Joomla\Component\Admin\Administrator\Dispatcher\Dispatcher->dispatch() C:\www\joomla4\libraries\src\Component\ComponentHelper.php:389
[22-Dec-2020 19:02:04 UTC] PHP   8. Joomla\Component\Admin\Administrator\Controller\DisplayController->execute() C:\www\joomla4\libraries\src\Dispatcher\ComponentDispatcher.php:146
[22-Dec-2020 19:02:04 UTC] PHP   9. Joomla\Component\Admin\Administrator\Controller\DisplayController->display() C:\www\joomla4\libraries\src\MVC\Controller\BaseController.php:729
[22-Dec-2020 19:02:04 UTC] PHP  10. Joomla\Component\Admin\Administrator\View\Profile\HtmlView->display() C:\www\joomla4\libraries\src\MVC\Controller\BaseController.php:691
[22-Dec-2020 19:02:04 UTC] PHP  11. Joomla\Component\Admin\Administrator\View\Profile\HtmlView->display() C:\www\joomla4\administrator\components\com_admin\src\View\Profile\HtmlView.php:98
[22-Dec-2020 19:02:04 UTC] PHP  12. Joomla\Component\Admin\Administrator\View\Profile\HtmlView->loadTemplate() C:\www\joomla4\libraries\src\MVC\View\HtmlView.php:218
[22-Dec-2020 19:02:04 UTC] PHP  13. include() C:\www\joomla4\libraries\src\MVC\View\HtmlView.php:429
[22-Dec-2020 19:02:04 UTC] PHP  14. Joomla\CMS\Layout\LayoutHelper::render() C:\www\joomla4\administrator\components\com_admin\tmpl\profile\edit.php:91
[22-Dec-2020 19:02:04 UTC] PHP  15. Joomla\CMS\Layout\FileLayout->render() C:\www\joomla4\libraries\src\Layout\LayoutHelper.php:73
[22-Dec-2020 19:02:04 UTC] PHP  16. include() C:\www\joomla4\libraries\src\Layout\FileLayout.php:128
[22-Dec-2020 19:02:04 UTC] PHP  17. Joomla\CMS\HTML\HTMLHelper::_() C:\www\joomla4\layouts\joomla\edit\params.php:149
[22-Dec-2020 19:02:04 UTC] PHP  18. Joomla\CMS\HTML\HTMLHelper::call() C:\www\joomla4\libraries\src\HTML\HTMLHelper.php:134
[22-Dec-2020 19:02:04 UTC] PHP  19. Joomla\CMS\HTML\Helpers\Bootstrap::addTab() C:\www\joomla4\libraries\src\HTML\HTMLHelper.php:322

[22-Dec-2020 19:02:04 UTC] PHP Notice:  Undefined index: Joomla\CMS\HTML\Helpers\Bootstrap::startTabSet in C:\www\joomla4\libraries\src\HTML\Helpers\Bootstrap.php on line 537
[22-Dec-2020 19:02:04 UTC] PHP Stack trace:
[22-Dec-2020 19:02:04 UTC] PHP   1. {main}() C:\www\joomla4\administrator\index.php:0
[22-Dec-2020 19:02:04 UTC] PHP   2. require_once() C:\www\joomla4\administrator\index.php:36
[22-Dec-2020 19:02:04 UTC] PHP   3. Joomla\CMS\Application\AdministratorApplication->execute() C:\www\joomla4\administrator\includes\app.php:63
[22-Dec-2020 19:02:04 UTC] PHP   4. Joomla\CMS\Application\AdministratorApplication->doExecute() C:\www\joomla4\libraries\src\Application\CMSApplication.php:266
[22-Dec-2020 19:02:04 UTC] PHP   5. Joomla\CMS\Application\AdministratorApplication->dispatch() C:\www\joomla4\libraries\src\Application\AdministratorApplication.php:185
[22-Dec-2020 19:02:04 UTC] PHP   6. Joomla\CMS\Component\ComponentHelper::renderComponent() C:\www\joomla4\libraries\src\Application\AdministratorApplication.php:142
[22-Dec-2020 19:02:04 UTC] PHP   7. Joomla\Component\Admin\Administrator\Dispatcher\Dispatcher->dispatch() C:\www\joomla4\libraries\src\Component\ComponentHelper.php:389
[22-Dec-2020 19:02:04 UTC] PHP   8. Joomla\Component\Admin\Administrator\Controller\DisplayController->execute() C:\www\joomla4\libraries\src\Dispatcher\ComponentDispatcher.php:146
[22-Dec-2020 19:02:04 UTC] PHP   9. Joomla\Component\Admin\Administrator\Controller\DisplayController->display() C:\www\joomla4\libraries\src\MVC\Controller\BaseController.php:729
[22-Dec-2020 19:02:04 UTC] PHP  10. Joomla\Component\Admin\Administrator\View\Profile\HtmlView->display() C:\www\joomla4\libraries\src\MVC\Controller\BaseController.php:691
[22-Dec-2020 19:02:04 UTC] PHP  11. Joomla\Component\Admin\Administrator\View\Profile\HtmlView->display() C:\www\joomla4\administrator\components\com_admin\src\View\Profile\HtmlView.php:98
[22-Dec-2020 19:02:04 UTC] PHP  12. Joomla\Component\Admin\Administrator\View\Profile\HtmlView->loadTemplate() C:\www\joomla4\libraries\src\MVC\View\HtmlView.php:218
[22-Dec-2020 19:02:04 UTC] PHP  13. include() C:\www\joomla4\libraries\src\MVC\View\HtmlView.php:429
[22-Dec-2020 19:02:04 UTC] PHP  14. Joomla\CMS\Layout\LayoutHelper::render() C:\www\joomla4\administrator\components\com_admin\tmpl\profile\edit.php:91
[22-Dec-2020 19:02:04 UTC] PHP  15. Joomla\CMS\Layout\FileLayout->render() C:\www\joomla4\libraries\src\Layout\LayoutHelper.php:73
[22-Dec-2020 19:02:04 UTC] PHP  16. include() C:\www\joomla4\libraries\src\Layout\FileLayout.php:128
[22-Dec-2020 19:02:04 UTC] PHP  17. Joomla\CMS\HTML\HTMLHelper::_() C:\www\joomla4\layouts\joomla\edit\params.php:149
[22-Dec-2020 19:02:04 UTC] PHP  18. Joomla\CMS\HTML\HTMLHelper::call() C:\www\joomla4\libraries\src\HTML\HTMLHelper.php:134
[22-Dec-2020 19:02:04 UTC] PHP  19. Joomla\CMS\HTML\Helpers\Bootstrap::addTab() C:\www\joomla4\libraries\src\HTML\HTMLHelper.php:322