CurrentRouteMatch::getCurrentRouteMatch throws TypeError when current request is null

In Drupal core changes are made on on 11.x (our main development branch) first, and are then back ported as needed according to the Core change policies → .

Ran the test-only feature

1) Drupal\Tests\Core\Routing\CurrentRouteMatchTest::testGetCurrentRouteObject
TypeError: Drupal\Core\Routing\CurrentRouteMatch::getRouteMatch(): Argument #1 ($request) must be of type Symfony\Component\HttpFoundation\Request, null given, called in /builds/issue/drupal-3536072/core/lib/Drupal/Core/Routing/CurrentRouteMatch.php on line 87
/builds/issue/drupal-3536072/core/lib/Drupal/Core/Routing/CurrentRouteMatch.php:99
/builds/issue/drupal-3536072/core/lib/Drupal/Core/Routing/CurrentRouteMatch.php:87
/builds/issue/drupal-3536072/core/tests/Drupal/Tests/Core/Routing/CurrentRouteMatchTest.php:80
ERRORS!
Tests: 10, Assertions: 25, Errors: 1, PHPUnit Deprecations: 11.
Exiting with EXIT_CODE=2

IS is clear (thank you!)

Think returning NullRouteMatch is a good compromise.

LGTM.

Left a comment, not changing status because it's a nit.