Fix await on null when test class don't have any tests

Author: maraf

src/Components/test/E2ETest/Infrastructure/ServerFixtures/WebHostServerFixture.cs

@@ -39,6 +39,10 @@ private async ValueTask DisposeCore()
         // This can be null if creating the webhost throws, we don't want to throw here and hide
         // the original exception.
         Host?.Dispose();
-        await Host?.StopAsync();
+
+        if (Host != null)
+        {
+            await Host.StopAsync();
+        }
     }
 }