Issue #3230507: Create build tests for case where site is using core recommended Composer project

tests/src/Build/AttendedCoreUpdateTest.php

@@ -106,7 +106,12 @@ class AttendedCoreUpdateTest extends AttendedUpdateTestBase {
       throw new \Exception($page->getContent());
     }
     $this->waitForBatchJob();
-    $assert_session->pageTextContains('Ready to update');
+    try {
+      $assert_session->pageTextContains('Ready to update');
+    }
+    catch (\Throwable $e) {
+      throw new \Exception($page->getContent());
+    }
     $page->pressButton('Continue');
     $this->waitForBatchJob();
     $assert_session->pageTextContains('Update complete!');