Invoke ensureOwnerAndJoined() first in GetFastestDeliveryTimeScope.result()

Author: SvenWoltmann

src/main/java/eu/happycoders/structuredconcurrency/demo3_suppliers/GetFastestDeliveryTimeScope.java

@@ -33,6 +33,8 @@ protected void handleComplete(Subtask<? extends SupplierDeliveryTime> subtask) {
   }
 
   public SupplierDeliveryTime result() throws SupplierDeliveryTimeCheckException {
+    ensureOwnerAndJoined();
+
     log("--> fastestDeliveryTime = " + fastestDeliveryTime);
     log("--> exceptions          = " + exceptions);