Legacy cleanup, part 2 (#3659)

* Legacy cleanup, part 2

There are still things that can be removed, those will be likely done in part three:
`The Return of the Cleanup` :)

Signed-off-by: nemerle <96597+nemerle@users.noreply.github.com>

* Fix windows build

Somehow there were some unfixed errors from enabled warnings?
I'm unsure if I've pulled repo in unstable state, or those were somehow
missed.

Signed-off-by: nemerle <96597+nemerle@users.noreply.github.com>

Gems/LyShine/Code/Editor/HierarchyHelpers.cpp

@@ -186,16 +186,20 @@ namespace HierarchyHelpers
                 if (listOfNewlyCreatedTopLevelElements.empty())
                 {
                     // This happens when the serialization version numbers DON'T match.
-                    QMessageBox(QMessageBox::Critical,
-                        "Error",
-                        QString("Failed to load elements. The serialization format is incompatible."),
-                        QMessageBox::Ok, widget->GetEditorWindow()).exec();
+                    QMessageBox(
+                        QMessageBox::Critical, "Error", QString("Failed to load elements. The serialization format is incompatible."), QMessageBox::Ok,
+                        widget->GetEditorWindow())
+                        .exec();
 
                     // Nothing more to do.
                     return LyShine::EntityArray();
                 }
 
-                completeListOfNewlyCreatedTopLevelElements.push_back(listOfNewlyCreatedTopLevelElements);
+                completeListOfNewlyCreatedTopLevelElements.insert(
+                    completeListOfNewlyCreatedTopLevelElements.end(),
+                    listOfNewlyCreatedTopLevelElements.begin(),
+                    listOfNewlyCreatedTopLevelElements.end()
+                );
             }
         }