QmlDesigner: Fix build with tests

Amends c3b90c0ce5.

Change-Id: I52eee2e9bcf78a1fb7315927efc861115b96a16a
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

src/plugins/qmldesigner/designercore/instances/nodeinstanceview.cpp

@@ -1147,9 +1147,13 @@ CreateSceneCommand NodeInstanceView::createCreateSceneCommand()
     if (stateNode.isValid() && stateNode.metaInfo().isSubclassOf("QtQuick.State", 1, 0))
         stateInstanceId = stateNode.internalId();
 
-    auto value = QmlDesigner::DesignerSettings::getValue(
-        QmlDesigner::DesignerSettingsKey::EDIT3DVIEW_BACKGROUND_COLOR);
-
+    auto value
+#ifndef QMLDESIGNER_TEST
+            = QmlDesigner::DesignerSettings::getValue(
+                QmlDesigner::DesignerSettingsKey::EDIT3DVIEW_BACKGROUND_COLOR);
+#else
+            = QColor();
+#endif
     QList<QColor> edit3dBackgroundColor;
     if (value.isValid())
         edit3dBackgroundColor = readBackgroundColorConfiguration(value);