PHPUnit 10 Assertion failure results in "Uncaught Error: Class "PHPUnit\Framework\TestFailure" not found" about behat HOT 1 OPEN

Hey, I saw the merged PR and I have a few follow up questions:

1. since it has been merged, shouldn't this ticket be closed (if the problem is now solved)?
2. looking at the code of the PR, I disagree a bit on how it works:
   1. In my understanding, PHPUnitExceptionStringer->supportsException should have prevented the original problem from happening, so I would recommend looking into why it wasn't
   2. The code of PHPUnitExceptionStringer->stringException is now a bit messier.. "if class exists return x; if class does not exist return z; else it must exist and therefore return y..", IMHO this would be clearer and more readable:

   switch (true) {
       case class_exists('PHPUnit\\Util\\ThrowableToStringMapper'):
           return trim(\PHPUnit\Util\ThrowableToStringMapper::map($exception));
   
       case class_exists('PHPUnit\\Framework\\TestFailure'):
           // PHPUnit assertion exceptions do not include expected / observed info in their
           // messages, but expect the test listeners to format that info like the following
           // (see e.g. PHPUnit_TextUI_ResultPrinter::printDefectTrace)
           return trim(\PHPUnit\Framework\TestFailure::exceptionToString($exception));
   
       case class_exists('PHPUnit_Framework_TestFailure'):
           return trim(\PHPUnit_Framework_TestFailure::exceptionToString($exception));
   
       default:
           // TODO this should also be somehow handled
   }

   It now also exposes the original flaw, which the patch didn't fix adequately IMO.
3. Shouldn't PHPUnitExceptionStringer->supportsException also be updated to handle the new formatter?

from behat.