QmlDesigner: Reset error messages wehen restarting puppet

We store generic error messages in the root node.
Those have to be reset.
Also we have to reset the type icon if there is no error anymore.

Change-Id: Ibe6274f651113f26aef6240bb9efa005862378f4
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/plugins/qmldesigner/components/navigator/navigatortreemodel.cpp

@@ -380,6 +380,7 @@ void NavigatorTreeModel::updateItemRow(const ModelNode &modelNode, ItemRow items
             items.idItem->setToolTip(QString::fromUtf8(modelNode.type()));
         else
             items.idItem->setToolTip(msgUnknownItem(QString::fromUtf8(modelNode.type())));
+        items.idItem->setIcon(getTypeIcon(modelNode));
     }
 
     blockItemChangedSignal(blockSignal);

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

@@ -199,6 +199,10 @@ void NodeInstanceView::handleCrash()
 
 void NodeInstanceView::restartProcess()
 {
+    if (rootNodeInstance().isValid())
+        rootNodeInstance().setError({});
+    emitInstanceErrorChange({});
+
     if (m_restartProcessTimerId)
         killTimer(m_restartProcessTimerId);