Assert that the request did not fail before following redirects

Otherwise the original error is hidden making this test failing
very hard to debug. This should also be improved in the other
tests that follow redirects.

(cherry picked from commit 5c5b651)

Author: eldering

webapp/tests/Unit/Controller/Jury/JuryControllerTestCase.php

@@ -300,6 +300,8 @@ public function testCheckAddEntityAdmin(array $element, array $expected): void
         $this->verifyPageResponse('GET', static::$baseUrl, 200);
         if (static::$add !== '') {
             $response = $this->helperSubmitFields($element);
+            static::assertLessThan(400, $this->client->getInternalResponse()->getStatusCode(),
+                                   $this->client->getInternalResponse()->getContent());
             $this->client->followRedirect();
             foreach ($element as $key => $value) {
                 if (!is_array($value) && !in_array($key, static::$overviewSingleNotShown)) {