Display failing URL in E2E crawling test

Try to debug how the failing page looked like in CI.
This is only relevant for CI as locally we can reproduce the test or
set the environment variable.

Author: vmcj

webapp/tests/E2E/Controller/ControllerRolesTraversalTest.php

@@ -224,7 +224,16 @@ public function visitWithNoContest(string $url, bool $dropdown): void
         $response = $this->client->getResponse();
         self::assertNotEquals(500, $response->getStatusCode(), sprintf('Failed at %s', $url));
         if ($dropdown && !str_contains($url, '/public')) {
-            self::assertSelectorExists('a#navbarDropdownContests:contains("no contest")');
+            try {
+                self::assertSelectorExists('a#navbarDropdownContests:contains("no contest")', "Failed at: " . $url);
+            } catch (\Exception $e) {
+                $gitlabArtifacts = getenv('GITLABARTIFACTS');
+                if ($gitlabArtifacts != '') {
+                    $fileHandler = fopen(sprintf("%s/%s", $gitlabArtifacts, str_replace('/', '_s_', $url)), 'w');
+                    fwrite($fileHandler, $response->getContent());
+                }
+                throw $e;
+            }
         }
     }